/// <summary>
 /// Allows adding new game screens
 /// </summary>
 /// <param name="gameScreen">Game screen</param>
 public static void AddScreen(GameScreen gameScreen)
 {
     if (ScreenList == null)
     {
         ScreenList = new List<GameScreen>();
     }
     ScreenList.Add(gameScreen);
     gameScreen.LoadAssets();
 }
 /// <summary>
 /// Allows removal of game screens
 /// </summary>
 /// <param name="gameScreen">Game screen</param>
 public static void RemoveScreen(GameScreen gameScreen)
 {
     gameScreen.UnloadAssets();
     ScreenList.Remove(gameScreen);
     if(ScreenList.Count < 1)
     AddScreen(new TestScreen());
 }
 /// <summary>
 /// Enables changing of the screens
 /// </summary>
 /// <param name="currentScreen">Current game screen</param>
 /// <param name="targetScreen">Target game screen</param>
 public static void ChangeScreens(GameScreen currentScreen, GameScreen targetScreen)
 {
     RemoveScreen(currentScreen);
         AddScreen(targetScreen);
 }