Made Colliders Generic

Made colliders generic. Implemented reference counting for colliders
(don't forget to allocate!). Got rid of some temporary code. Made copy
constructor for PhysicsObject. Gave PhysicsObject an operator=.
Revert "Made Colliders Generic"

This reverts commit 4f3b139a311085f57deea2bcb31a8d369cf0452f.
Made Colliders Generic

Made colliders generic. Implemented reference counting for colliders
(don't forget to allocate!). Got rid of some temporary code. Made copy
constructor for PhysicsObject. Gave PhysicsObject an operator=, etc.