Resolved some reported issues.

- Threaded OGG loading (in addition to MP3) to eliminate delays in song select menu. (reported by xasuma)
- Changed default OSZ unpacking location to a "SongPacks" directory to prevent unintended unpacking. (reported by Lanturn)
- Fixed a null pointer for a corner case in 'getRandomNode()'. (reported by @iceblade112)

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

src/itdelatrisu/opsu/states/SongMenu.java

@@ -606,7 +606,7 @@ public class SongMenu extends BasicGameState {
 	 * @param osu the OsuFile to send to the game
 	 */
 	private void startGame() {
-		if (MusicController.isConverting())
+		if (MusicController.isTrackLoading())
 			return;
 
 		SoundController.playSound(SoundController.SOUND_MENUHIT);