sync controls cleanup:

move sync display/saving out of complicated ScreenGameplay
  show sync UI in editor playback as well as gameplay
  revert sync from in-memory backup, not from disk
  move more functions into debug overlay

stepmania/src/Screen.cpp

@@ -17,6 +17,8 @@ Screen::Screen( CString sName )
 {
 	SetName( sName );
 	m_bIsTransparent = false;
+
+	ALLOW_OPERATOR_MENU_BUTTON.Load( sName, "AllowOperatorMenuButton" );
 }
 
 Screen::~Screen()