public void UnloadScreen(Screen screen)
 {
     switch(screen.ScreenID)
     {
         case ScreenIdentity.Battle:
             battleScreen = new BattleScreen();
             battleScreen.Initialise();
             nextScreen = battleScreen;
             break;
     }
 }
        public void Initialise()
        {
            mapScreen = new MapScreen();
            mapScreen.Initialise();
            battleScreen = new BattleScreen();
            battleScreen.Initialise();
            //thanksForPlayingScreen = new ThanksForPlayingScreen();
            //thanksForPlayingScreen.Initialise();

            currentScreen = mapScreen;
            screenTransitionState = ScreenTransitionState.NewScreenIn;
        }