Introduced QuadTrees, New Collision Detection

- Introduced fully functional QuadTree class
- Introduced fully functional Axis-Aligned Bounding Box (AABB) class
- Updated all collision methods to use AABB collision method (faster
than native JSFML method)
- Updated collision between entities to be a little more precise
(entities now at least touch each other before properly colliding)
- Introduced CRandom, CVector, and CPhysics, utility classes that handle
various useful functions.
- Added asteroid destruction of size 2 asteroids as proof of concept
- Will add destruction of all size asteroids when QuadTree collision is
full implemented