Added possibility to specifiy an initial bounding box to KD-tree.

This should not really matter, but for some reason it does. Seems some bugs remain.
Reinstated octree, but something is still wrong.
Added some debug output to the hit octree.
Minor cleanup to octree (fixed signed/unsigned warning, note about bug).
Re-added original HitOctree as HitQuadtree, reverted static collisions to use this one.
Cleanup and some optimizations to quadtree.

Should now be reasonably close to original collision behavior.