Added Main menu

* Play Button
* Settings Button
* Quit Button

Assets/Scripts/MainMenu.cs

@@ -0,0 +1,20 @@
+using UnityEngine;
+using UnityEngine.SceneManagement;
+
+public class MainMenu : MonoBehaviour {
+    
+    /**
+     * Play the game
+     * (Load the MainScene)
+     */
+    public void PlayGame() {
+        SceneManager.LoadScene("MainScene");
+    }
+
+    /**
+     * Quit the Application appropriately
+     */
+    public void QuitGame() {
+        Application.Quit();
+    }
+}