Options state refactoring.

- Renamed Options state into OptionsMenu, and created Options class for solely handling user options.  Moved everything unrelated to the actual options menu into the static Options class.
- OptionsMenu no longer has static fields.
- Refactored option tabs into an enum, which makes the code much cleaner.

Also fixed a bug where global volume wasn't being used on container initialization.

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

src/itdelatrisu/opsu/states/Game.java

@@ -24,6 +24,7 @@ import itdelatrisu.opsu.GameMod;
 import itdelatrisu.opsu.GameScore;
 import itdelatrisu.opsu.MenuButton;
 import itdelatrisu.opsu.Opsu;
+import itdelatrisu.opsu.Options;
 import itdelatrisu.opsu.OsuFile;
 import itdelatrisu.opsu.OsuHitObject;
 import itdelatrisu.opsu.OsuTimingPoint;