Major re-write of N-dim bitmap packing for bgq

Major re-write of the algorithm used to allocate N-dimensional
objects using bitmaps: Added argument that controls whether
passthroughs can be used in each specific dimension. Added
coordinates of starting location of block in each dimension.
Added element count (geometry) in each dimension. Added offset
so that scan can be continued and generated alternative placements
without re-testing placements already tested.