merge OverlayInput into Input. overlay screens can still intercept input if they want.

src/ScreenSyncOverlay.h

@@ -10,7 +10,7 @@ class ScreenSyncOverlay : public Screen
 public:
 	virtual void Init();
 	
-	bool OverlayInput( const InputEventPlus &input );
+	bool Input( const InputEventPlus &input );
 
 	void Update( float fDeltaTime );