Technical Field The present invention relates to container comprising adjoining walls and a base according to the preamble of claim 1 and a use of at least one section of the container according to the preamble of claim 18. Description of Prior Art Containers using collapsible walls adjoining a base for transporting and storing various items/goods are well known. The containers are filled with the goods, transported to a location where the goods are unloaded and the walls of the empty containers are then folded into a position in which the container height is considerably lower taking up less space when transported back to be filled again. The container walls are often arranged in two pairs of walls being orthogonal/perpendicular to each other with each wall placed opposite the other side wall in the associated wall pair. The walls are often pivotally attached at their lower ends by means of at least one hinge to the base or deck of the container so that they can be folded from an upright or essentially vertical position for storage, washing or filling to a lying essentially horizontal position for transport or storage. In the latter position it is important that the walls are secured to the container and do not accidentally come loose during the handling of the folded container. This is especially important for larger and also very large containers, e.g. large "heavy-duty" containers. One type of prior art hinge for detachably attaching pivotable walls has at least one projection arranged on the movable wall in the form of a pin fitting into a pivot/swivel/tilting seat in the form of at least one hole in the container. The pin and the hole extend in directions being parallel with the adjoining edges of the walls and the container, i.e. the base. The walls are attached to the container by first assembling the walls in a first wall pair by inclining the first walls, then moving them in a first direction being orthogonal to any of the walls in the other side wall pair not yet mounted, i.e. in the longitudinal direction of the first wall pair, while the hinge pin and the hole mate until the hinge pin abut the opening of the hole. After that, the first walls are folded down inwards of the container to their lying position and the other second walls of the second wall pair are attached in the same way as the first wall pair but folded up to their upright position, whereby the first walls finally are erected to their upright position and the walls are secured together in the upright positions in known ways . Another example of a prior art container has foldable side walls with hinges formed by seats on the side walls mating with hinge pins or projections on the container. The side wall seats are "half seats", i.e. they only surround about half the circumference of the hinge pins on the container when in engagement. The hinges comprise inner seats facing inwards of the container and end/outer seats facing away from the container. The end seats keep the side walls in place when the side walls are folded. These prior art hinges have severe disadvantages . One prior art hinge is very difficult to use when detaching only one wall in a first wall pair from the container while the adjoining walls in the other wall pair towards which the first wall has to be moved when detached is kept upright because the adjoining walls block the movement of the first wall. The other prior art hinge has for example disadvantages in that only the inner seats are load carrying, and that the side walls have to be attached or detached from the container by using force and great effort, and also stresses the material in the hinges. Larger prior art containers having heavy and/or cumbersome side walls put on high loads on the hinges stressing them even more. Summary of the Invention An object of the present invention is to provide a solution to the above mentioned problems by presenting ah improved container with at least one foldable section of at least one wall. According to the invention, this object is achieved by a device of the type stated by way of introduction, which has the features that appear from claim 1 and 18, preferred embodiments being defined in the appended claims 2-17 and 19. By the improved container and hinge according to the invention, several advantages are obtained. The walls are detachably attached to the container in a more secure way reducing the risk of having the walls accidentally coming loose from the container further. This is especially important for larger containers with heavier side walls because their hinges must take-up higher loads, weights, and/or forces when the heavier side walls are handled. Moreover, the step of moving the walls in the lateral direction towards the adjoining walls is eliminated, whereby one wall may be detached from the container without having to fold or detach another adjoining wall blocking the wall to be detached. Furthermore, the force used for detaching or attaching the side walls to the container is reduced, and the detachment and attachment of the wall may be done without any tools. Brief Description of the Drawings The present invention will now be described in more detail with reference to the enclosed drawings, in which: Fig 1 is a view in perspective of a container according to the invention, Fig 2 is a view in perspective of a corner area of the container in fig 1 with upright side walls, Fig 3 is an enlarged view according to fig 2, Fig 4 is a view in perspective of the corner area in figs 2 and 3 from a somewhat different angle, Fig 5 is an enlarged view according to fig 4, Fig 6 is an enlarged detailed view of fig 5, Fig 7 is a view in perspective of the corner area in figs 4-6 with an inclined side wall, Fig 8 is an enlarged view according to fig 7, and Fig 9 is an enlarged detailed view of fig 8. Detailed Desription of the Invention Figs 1-9 illustrate a first embodiment of a collapsible container 10 according to the invention comprising foldable side walls and/or wall sections 20,30,21,31 adjoining a base 40, wherein at least one section 21,31 of at least one detachable and foldable wall 20,30 is pivotally and detachably attached to the container by means of at least one hinge 50. The wall sections can be one or more whole walls 20, 30 or only a part of one or more walls, e.g. an access door, a hatch or a gate at the upper, lower or middle part of the wall, and/or the walls can be fixed with only the wall access doors being foldable and/or detachable. The hinge 50 is formed by at least one recess 60 with an orifice 61. The recess is a groove on the container 10 mating with at least one projection 70 on the wall 20,30 and/or wall section 21,31. In this, embodiment shown in figs 1-9 there are four recesses 60 and four projections 70 but only one of each may of course be used. There are also only shown two wall doors or sections 21,31 but any other number of doors may be used, e.g. the container 10 may be equipped with no access doors 21,31, one access door in each side wall 20,30, or only one access door in one wall, as is readily understood by a skilled person. The movement and detachment or attachment of the walls 20,30 or wall sections 21,31 will be explained only with reference to the walls 20,30 but a skilled person will of course understand that the wall sections 21,31 are used in the same way. The projection 70 shown in figs 2-9 has a cross- section similar to a cross with at least two widths Wi and W2 (shown in detail in figs 6 and 9), so that when the wall 20,30 or wall section 21,31 is inclined at an angular position (shown in figs 7-9) between a lying position (not shown) and an erected/upright position (shown in figs 1-6) , the smallest width W2 of the projection 70 is smaller than the inside measure of the recess 60, i.e. its orifice 61, and aligned with this orifice and the longitudinal extension of the recess for attaching or detaching the wall 20,30 with at least a part of its bottom longitudinal wall edge adjoining at least a part of a longitudinal edge of the base 40. The base has an upturned fixed edge similar to a flange at its edge adjoining the lower part of the wall 20,30, so that the wall is supported from the outside by abutting this deck flange in its upright position. The smallest width W2 of the projection 70 is smaller than the inside measure of the recess 60 (shown in figs 7-9) when the wall 20,30 is inclined in relation to its upright position at an angle of 45°. An angle of 45° is preferred because it is furthest away from the horizontal folded state (0°) and the upright state (90°) for the wall. Furthermore, the projection 70 extends in a direction being parallel with the plane of the wall giving a direction of movement for the wall being perpendicular to the adjoining edges of the wall and the base 40. The projection 70 is orientated so that the smallest width W2 is in horizontal alignment with the orifice of the recess 60 when the wall 20,30 is inclined at the 45° angle in relation to its upright position. The orifice 61 of the recess 60 faces the interior of the container 10 and extends in the horizontal direction, i.e. in parallel with the plane of the base 40, and the recess has the form of a groove extending in the vertical direction, i.e. in parallel with the plane of the wall 20,30, whereby the opening 61 of the groove 60 is perpendicular/orthogonal to the extension of the groove. This orientation of the orifice 61 and the groove means that the wall and the projections 70 are moved in two directions being orthogonal to each other and are only moved in directions being parallel to the planes of the adjoining walls and never towards the adjoining walls, whereby these do not block or hinder the detachment or attachment of the wall 20,30. The orifice 61 may of course face away from the container 10 in other embodiments, e.g. when the walls are moved outwards of the container during opening and/or folding. As shown in this embodiment, the projection 70 has a cross-section similar to a cross but may instead have a cross-section similar to a star, a dog bone, or an elliptic, square, quadratic, rectangular, or triangular cross-section. The projection 70 is arranged on the wall 20,30 or wall section 21,31 but could instead be arranged on the container 10, i.e. the base/deck 40, and the recess 60, i.e. the pivot/swivel/tilting seat, could be arranged on the wall or the wall section. The hinge 50 also comprises at least one additional projection 80 for each hinge projection 60. This second projection 80 has a guiding, locking and stabilizing function in that it has a shape fitting into the opening 61 of the recess 60 and is inserted therein when the wall 20,30 is in its upright position. The guide projection 80 then locks/holds the wall in the vertical direction so that the risk of having the wall coming loose by undesired movement upwards in the verticaal direction is reduced further. The guide projection 80 has a L-shaped cross-section and is arranged above the first hinge projection 70 that is in keying engagement with the container 10. When using the wall 20,30 in the container 10 the wall section is moved only in any direction being essentially perpendicular to the adjoining edges of the wall section and the base 40 into a position in which the wall section is inclined at an angular position in relation to its upright position between a lying position and an erected position when it is attached to or detached from the container. Preferably, the wall 20,30 is moved into the inclined position with the angle of 45° in relation to its upright position for attaching or detaching it to or from the container. In one embodiment of the invention, the largest width Wi of the projection 70 is larger than the inside measure of the recess 60, i.e. its opening 61. In another embodiment, the projection may have a width adapted to the inside of the recess 60 so that the wall 20,30 will not rattle and/or vibrate inside the recess 60 in its upright position during handling/transport of the container. This hinge 50 according to the invention may be used with other orientations instead of the shown horizontal direction. It can be used for at least one cover/lid (not shown) over the container 10 or for the walls, the cover being attached at the upper side edges adjoining the walls and the cover instead of the lower side edges adjoining the walls and the base 40. The hinge 50 can also be arranged at the corner areas between the side ■ edges of the walls 20,30 extending in the vertical direction, whereby the walls are pivoted in the same direction as car doors or similar doors. The 45°-angle for detachment and attachment of the walls 20,21,30,31 is preferred because then the risk of having the walls inadvertently coming loose from the container is the smallest but any other suitable angle could of course be used, e.g. 22.5°, 35°, or 40°. The openingen/orifice 61 of the recess 60 may also have another orientation, e.g. the orifice could face upwards and the recess could extend in the horizontal direction. The most important is that the projection 70 has one width W2 for passing through the opening and one width Wi for locking/holding the wall 20,21,30,31 in place in its upright position.