Added FlipPosition() in MsseageSender

-The function takes a Rect and the height of the window
-It returns the a Vector2f
	-x value is simpley the x of the rect
	-y value is window height - rect.y - rect.h
-This should flip the position properly
-Used for all objects except Tiles
Added MessageSender.cpp

-Moved function from header to cpp file
-Added GameManager to build script ( build/DXBall.pro )
-PhysicsManager.cpp was added to build scrupt, but the change wasn't
commited, added it now.