* Replace square in center of level with stationary ball
* Improve collision demo
- Collisions between balls are smoother.
- Fixed an issue with collision bounds not being set properly. (This is what made the collision appear unsmooth)
* Created unit test project for collisions.
* Started on tests
* Created unit test project for collisions.
* Started on tests
* Update collision test
* CollisionInfo docs
* More docs for CollisionGrid and Cell
* Fix obsolete warning for RectangleF.Intersect
* Summary for CollisionGrid and CollisionGridCell
* QuadTree collision implemented
- Ported from C++ from Game Physics Cookbook chapter 6, 2D Optimizations
* Small refactor for QuadTree naming
* First tests for QuadTree
* Fix test
* COde Cleanup
* Added DefaultMaxObjectsPerNode
* Add missed Query code
* Insert Tests and bugfix
* Fix bug with QuadTree.Shake
* Fix namespaces
* Query tests and fix
* Additional test for Query
* Initial QuadTreeCollision Component
* Basic collision demo working
* Spikey ball colliding with walls
* Improved the collision demo
* Update QuadTree
* Added comment for CollisionComponent
* Ignore test that needs fixed
* Rename QuadTree to Quadtree
* Fix penetration vector
* Update to 2.0 and xUnit