Quick fixes.

- Fixed a crash when closing the application in the ranking screen when viewing a score.
- Fixed a minor bug where OsuGroupList fields were not being erased upon restart.
- Dim the track volume by 50% when viewing a score.

Signed-off-by: Jeffrey Han <itdelatrisu@gmail.com>

src/itdelatrisu/opsu/states/SongMenu.java

@@ -777,6 +777,10 @@ public class SongMenu extends BasicGameState {
 		else if (MusicController.isPaused())
 			MusicController.resume();
 
+		// undim track
+		if (MusicController.isTrackDimmed())
+			MusicController.toggleTrackDimmed(1f);
+
 		// reset song stack
 		randomStack = new Stack<SongNode>();