Major fixes + Added LuaCollisionSystem

Fixes:

• PhysicsSystem now properly removes deleted GameObjects from its quadtree (fixing memory corruption issues)
• LuaSystem now buffers entity creations and removals until end of frame (fixing memory corruption issues)

Addition:

• LuaCollisionSystem: provides access to Collision datapackets from scripts. Serves as an example of how to provide access to any type of datapacket