KAYAK WITH INCREASED STABILITY AND CONTROL Background of the Invention The invention relates to a kayak used in white water recreation, as well as river, lake, stream and ocean use. In particular, the invention relates to a kayak which provides more room at the midsection for the paddle, and is inherently more directionally stable making the kayak easier to control while having wave stability. With the increasing popularity of recreation and sea kayaking, the provision of water craft which is suitable, safe, and structurally sufficient for this type of recreation is a problem to which considerable attention need be given. In particular, high performance kayaks have been provided which are constructed from a flexible plastic skin to yield upon impact with the water and various obstacles encountered in white water conditions such as shown in United States Patent nos. 4,681 ,060; 4,480,579; 4,407,216; and 4,227,272 invented by the present applicant. The typical touring/sea kayak has a "Swede" hull design. The Swede design has a narrow profile for speed with its widest point at or aft of the paddler, but is relatively less stable and is more difficult to paddle in a straight line. With kayak type watercraft becoming more popular, its application has spread from white water use to general use in rivers, lakes, ponds, and the ocean, and to boaters who are less interested in high performance kayaking. For example, family use, use by senior adults, and others less interested in high performance and more interested in ease of handling, has created the need for kayaks with different characteristics. Moreover, high performance kayaks are highly unstable when the paddler is entering and exiting the craft. Accordingly an object of the present invention is to provide a kayak having increased stability and ease of handling yet has certain high performance characteristics as well. Another object of the present invention is to provide a kayak having a hull providing increased stability while stationary in the water yet which provides reduced drag and high speed performance moving though the water. Yet another object of the invention is to provide a unique kayak hull construction having a form that provides increased directional stability and wave (roll) stability. Still another object of the present invention is to provide a kayak hull having a wider upper hull providing stability when the kayak is stationary in the water and roll stability when paddling, and a narrower lower hull which displaces water and produces less drag when the kayak is moving forward sufficiently for higher speed performance. Summary of the Invention The above objectives are accomplished according to the present invention by a kayak having a hull configuration which provided increased directional and roll stability. The hull has a deck with a cockpit for accommodating a kayaker in a seated position; a bow section fore of the cockpit; and a stern section aft of the cockpit. Advantageously, the hull includes a lower hull extending generally the length of the kayak along the bottom of the hull, and an upper hull extending generally the length of the kayak formed above the lower hull. The lower hull has a width less than the corresponding width of the upper hull along a length of the kayak to define hull wings projecting generally laterally on opposing sides of the upper hull. A generally stepped-down profile is created by the transition of the wider upper hull down to the narrower lower hull along a length of the kayak so that the hull wings provide wave and roll stability. The upper hull has a characteristic width along the bow section which is wider than a width of a midsection of the kayak hull where the cockpit is located. The lower hull has a bow section which is greater than or equal to a width of a stern section of the lower hull so that directional stability is provided. The hull includes a longitudinal transition line where the upper hull wings transition into the lower hull. A characteristic wave is produced by the hull having an undulating profile formed underneath the hull wings generally along the transition line as the hull is paddled through the water at sufficient speeds. Advantageously, the hull has a generally stepped-down cross-sectional profile which includes the upper hull curving downwards on opposing sides of the hull terminating at the lower hull along the transition line. Smooth, generally horizontal, ledges of the hull wings of the upper hull beginning at the transition line curve upwards terminating at the hull deck. The lower hull has a characteristic bow width, midsection width, and stem width. The characteristic bow width is greater than the midsection width. Preferably, the bow width is generally greater than the stern width to provide a "fish" form hull. In some cases, it may be desirable to make either the stern widths generally equal to the midsection width. The upper hull section has a characteristic bow width, midsection width, and stern width where one or both of the bow and stern width are greater than corresponding widths of the lower hull along a length of the kayak hull. Description of the Drawings The construction designed to carry out the invention will hereinafter be described, together with other features thereof. The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings forming a part thereof, wherein an example of the invention is shown and wherein: Figure 1 is a perspective view of a stable kayak constructed according to the invention; Figure 2A is a sectional view taken along line 2A-2A of Figure 1 ; Figure 2B is a sectional view taken along line 2B-2B of Figure 1 ; Figure 2C is a sectional view taken along line 2C-2C of Figure 1 ; Figure 3 is an front view of the bow of a stable kayak construction according to the invention; Figure 4 is an end view taken from the stern of a stable kayak construction according to the invention; Figure 5 is a bottom plan view of a kayak constructed according to the present invention; Figure 6 is a top plan view of a kayak constructed according to the present invention; Figure 7B is a side elevation of a kayak according to the invention illustrating the hull displacement when relatively still in the water; and Figure 7A is a side elevation of a kayak constructed according to the present invention illustrating a characteristic wave having a bow wave, trough wave, and secondary wave when the kayak is moving at traveling speeds through the water. Description of a Preferred Embodiment Referring now in more detail to the drawings, the invention will now be described in more detail. Figure 1 illustrates a kayak, designated generally as A, constructed according to the invention in order to provide increased stability and performance, among other things. Kayak A includes a bow section 12 and a stern section 14. A kayak hull, designated generally as 10, includes a deck 16 having a bow deck section 18 and a stern deck section 20. A cockpit, designated generally as 22, is formed in deck 16 and includes a cockpit opening 24 and a seat (not shown) to accommodate a kayaker in a seated position. The kayak opening includes a flange 26 around the periphery of the opening. Kayak hull 10 includes a lower hull 30 and an upper hull 32. Lower hull 30 is narrower than upper hull 32 for efficiency. Preferably lower hull 30 has a design generally referred as a "fish" form herein where the hull is wider fore of the cockpit along bow section 12 than aft of the cockpit along stern section 14. The fish form is somewhat analogous to the shape of a "fish," and is designated generally as 28 in the drawings (Figure 5). Upper hull 32 of the kayak has a shape, designated generally as 33, somewhat analogous to the shape of a "peanut" hull (Figures 5 and 6). In accordance with the present invention, in its lateral cross-section, hull 10 has a "stepped" profile along its length, as can best be seen in Figures 2A through 4. The profile includes wider upper hull 32 stepping down inwardly to lower hull 30 of the above described fish form. The stepped profile is defined by lateral hull wings 32a and 32b on each side of upper hull section 32 which displace water at midsection 15, and at bow tip 12a, and stern tip 14a, when the kayak is occupied and stationary to provide a more stable hull profile for entering or exiting the kayak, as well as stable performance at low speeds. A longitudinal transition line 35 is defined between the upper and lower hulls generally at the point or line from which the hull wings transition into the lower hull section. It can thus best be seen from Figures 2A-2C and 5 that lower hull 30 is generally narrower than upper hull 32 along the length of the kayak hull, as more particularly described below. The sinkage of kayak hull 10 is designed so that only narrower, lower hull 30 displaces water during paddling for reduced drag and increased efficiency. Upper hull 30 provides roll and wave stability by displacing water to stabilize the hull when the kayak rolls sufficiently about its longitudinal axis. For example, for a prescribed load, e.g., 220 lbs., lower hull 30 is designed so that the water displacement line stays about %" below transition line 35. As can best be seen in Figure 5 upper hull 32 has a characteristic bow width W1 , a midsection cockpit width W3, and stern width W5 profile defined generally midpoint of each section. Preferably, the width profile W1 and W5 are greater than the width W3 to provide the generally "peanut" form for the upper hull. In the peanut form, generally convex side sections 31a and 31b are formed for ease of paddling. Lower hull 30 includes a characteristic bow width W2, midsection width W4, and stem width W6. In the "fish" form. In the lower hull width W2 is greater than W4 and W6, and width W4 is greater than or equal to W6. In other words, lower hull is widest fore of the cockpit or midsection and tapers rearward to the end of the lower hull. It has been found, according to the invention, that this fish form design is inherently more directionally stable making the kayak easier to keep in a straight line direction when moving through the water. In addition, the narrow hull provides a less wetted surface, therefore less friction, resulting in more speed for equal effort through the water. In the present invention, the hull wings provide roll stability in the overall design. In the "swede" form, the bow width is smaller than or equal to the midsection width, and smaller than the stern width. Referring now to Figures 2A, 2B, and 2C, the waterline displacements of the kayak hull in operation will now be described. Waterline 33 shows displacement during generally stationary operation and waterline 37 shows paddling operation at sufficient speeds to create a characteristic wave 34 along the hull. Figure 2A illustrates a bow section of hull 10 in the water as taken along line 2A-2A of Figure 1. When the kayak is occupied and in a stationary operation, that is still or moving slowly in the water, the waterline of the hull is shown generally at 33 on either side of the kayak. Figure 2B shows a stern section of hull 10 taken along line 2B-2B of Figure 1 in stationary operation wherein the water displacement is shown at line 33. Figure 2C shows the waterline 33 of the hull in stationary operation at the midsection of the hull taken along line 2C-2C of Figure 1. As can best be seen in Figure 2C, upper hull wings 32a and 32b contact the water at line 33 to provide adequate lateral stability for a boater to safely enter and exit the kayak. During these maneuvers, kayak roll will be stabilized by the hull wings displacing water if the kayak rolls to one side or the other. During paddle operation, i.e., the kayak being paddled at characteristic speeds, the water displacement line is illustrated at 37. In Figures 2A, 2B, and 2C, it can be seen that operational waterline 37 generally follows transition line 35 underneath the hull wings so that the hull wings provide roll stability if the kayak hull rolls to either side or is rocked by a wave. As the kayak is paddled and paddled faster in paddle operation, characteristic wave 34 is developed by the kayak bow pushing the water aside. As can best be seen in Figure 7A, wave 34 includes a bow wave 34a rising along bow 12, a wave trough 34b formed generally along midsection 15, and a secondary wave 34c formed along stern 14 of kayak hull 10. Wave 34 has a sinusoidal form which rises from bow tip 12a along the bow at 34a, falls to a trough 34b at the midsection, and rises again along the stern at 34c falling off to stern tip 14a. The wave moves generally along narrow, lower hull section 30 underneath hull wings 32a, 32b, along transition line 35. The hull is designed so that wave 34 is created under the hull wings along the length of the kayak. The wider upper hull is not wetted as the narrow hull displaces water in paddle operation. However, if the kayak should lean or roll toward the left or right sufficiently, the hull wings correspondingly displace more or less water to automatically return the kayak to a stable upright position. Thus, both directional and roll stability are provided by the unique combination of the lower and upper hulls as well as higher performance speeds. The upper hull design, i.e. peanut form, also allows the kayaker more room during paddling, or when performing a maneuver commonly referred to as an "Eskimo" roll because of narrower midsection 15. Thus, it can be seen that an advantageous construction can be had for a kayak wherein a fish form provides a narrow lower hull for performance and directional stability. Roll stability when stationary is provided by laterally extending hull wings of the upper hull. Roll and wave stability are provided when the kayak is moving through the water when the hull wings roll to one side causing water displacement and stabilization in much the same way as training wheels provide stability on a bicycle. While a preferred embodiment of the invention has been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims.