rectint: fix for non-overlapping rectangle, and support ND boxes (bug #44904) * scripts/geometry/rectint.m: it was giving incorrect results (not zero) when the coordinates for X overlapped but the Y did not (added tests for this bug). This is a complete rewrite of the function. The new version performs approximately 1000 times faster and adds supports N dimensional boxes in which case it measures the volume or hypervolume of the hypervolume intersections. * NEWS: make note that rectint() now supports ND.