Changed collision detection such that each object has a state
Merge branch 'master' into collision_state
added collide to background surface to fix build
Merge remote-tracking branch 'origin/collision_state'

Conflicts (solved):
	Game/Game/BackgroundTerrain.cpp
	Game/Game/Boss.h
	Game/Game/GameEngine.cpp
	Game/Game/OpponentTank.h
	Game/Game/WorldObject.h