simplified collision system a bit. There is no longer the concept of BoxCollider and CircleCollider. Just a general Collider whose CollisionShape implementation determines its type. This keeps it more consistent with the RigidBody system.
fixed bug with ComponentsPanel painting.
fixed bug where app wasn't closing properly.
fixed bug where app wasn't closing properly from menu.

added editor support for RigidBody and Collider components.
fixed another exit bug
fixed save/load bug with Collider and RigidBody and fixed bug with RigidBody where reselecting one in the component list would reset the associated material.
Merge pull request #52 from jonbonazza/master

bug fixes and physics components in editor