A major feature lacking in the octree was proper support for setting visibility / activation. This meant that invisible objects were still causing lots of processing in the tree unnecessarily.
This PR adds proper support for activation, items are temporarily removed from the tree and collision detection when inactive.
When set_static is called on a newly added object, the forced collision
check in BVH set_pairable was using an empty AABB, which caused
unnecessary collision checks at the origin, then a call to move was
checking again at the right position.
These changes ensure broadphase objects are added to the BVH tree with
proper AABB so collision checks are correctly done right away.
Octree & Basic broadphase trees are not affected by these changes.
Complete rewrite of spatial partitioning using a bounding volume hierarchy rather than octree.
Switchable in project settings between using octree or BVH for rendering and physics.
