Changed character, Added GameOverScene and MainMenuScene, Organize scene using SceneManager

Changed character, Added GameOverScene and MainMenuScene, Organize
scene using SceneManager.
Changed some codes.
Changed character. Added Scenes.

Made the character into its shape.
Scenes added: MainMenu, GameOver, SceneManager.
Scenes. Character Added.

Made the character into its shape.
Scenes added: MainMenu, GameOver, SceneManager.