Return in aabb an axis aligned bounding box that surrounds the given geom. The aabb array has elements (minx, maxx, miny, maxy, minz, maxz). If the geom is a space, a bounding box that surrounds all contained geoms is returned. This function may return a pre-computed cached bounding box, if it can determine that the geom has not moved since the last time the bounding box was computed.