more refactoring, removed PhysicsInterface, cleaned up demos to make use of btDynamicsWorld derived classes.

removed two cached optimizations, type in btTransform and cached inverse transform (todo: test performance impact)
committed fixes that make the code adhere to 'who creates it, also destroys it'

src/BulletDynamics/Dynamics/btDynamicsWorld.h

@@ -40,11 +40,16 @@ class btDynamicsWorld : public btCollisionWorld
 		///stepSimulation proceeds the simulation over timeStep units
 		virtual void	stepSimulation( float timeStep) = 0;
 				
+		virtual void	updateAabbs() = 0;
 				
 		virtual void	addConstraint(btTypedConstraint* constraint) {};
 
 		virtual void	removeConstraint(btTypedConstraint* constraint) {};
-					
+
+		virtual void	setDebugDrawer(btIDebugDraw*	debugDrawer) = 0;
+
+		virtual btIDebugDraw*	getDebugDrawer() = 0;
+
 };
 
 #endif //BT_DYNAMICS_WORLD_H