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/GameMod.java

@@ -65,7 +65,7 @@ public enum GameMod {
 	private boolean active = false;
 
 	/**
-	 * The button containing the mod image (displayed in Options screen).
+	 * The button containing the mod image (displayed in OptionsMenu screen).
 	 */
 	private MenuButton button;