Use Init() for all screens, so we can set state before the base class

members are loaded--they'll see resets, score finalization, etc.  It
also results in smaller code, due to a g++ bug that causes constructors
to be emitted several times.

stepmania/src/ScreenSystemLayer.h

@@ -28,6 +28,7 @@ class ScreenSystemLayer : public Screen
 
 public:
 	ScreenSystemLayer();
+	virtual void Init();
 	void SystemMessage( const CString &sMessage );
 	void SystemMessageNoAnimate( const CString &sMessage );
 	void ReloadCreditsText();