public GestorPantallas()
        {
            graphics = new GraphicsDeviceManager(this);
            graphics.PreferredBackBufferWidth = 800;
            graphics.PreferredBackBufferHeight = 600;
            Content.RootDirectory = "Content";

            miAyuda = new Ayuda(Content);
            misOpciones = new Opciones(Content);
            miAnimacion = new AnimacionFinDeJuego(Content);
            miPresentacion = new Presentacion(graphics, Content);
            pantallaCreditos = new Creditos(graphics, Content);
            miPartida = new Partida(graphics, Content);
            modo = MODO_PRESENT;
        }