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/audio/MusicController.java

@@ -289,10 +289,11 @@ public class MusicController {
 
 	/**
 	 * Toggles the volume dim state of the current track.
+	 * @param multiplier the volume multiplier when the track is dimmed
 	 */
-	public static void toggleTrackDimmed() {
+	public static void toggleTrackDimmed(float multiplier) {
 		float volume = Options.getMusicVolume() * Options.getMasterVolume();
-		setVolume((trackDimmed) ? volume : volume / 3f);
+		setVolume((trackDimmed) ? volume : volume * multiplier);
 		trackDimmed = !trackDimmed;
 	}