change: Switched the state controller and scene controller to a singleton class

This doesnt' change any of the logic, but simplifies a lot of the main
game loop code.

Many things still rely on the singleton class, but shouldn't so this
will be fixed in a later commit

Assets/Scripts/SceneController.cs

@@ -7,38 +7,46 @@ using UnityEngine.UI;
 public class SceneController : MonoBehaviour
 {
 
+    public static SceneController Instance = null;
+
     // this object will always exist!
-    void Awake() {
-        // check to see if a state controller already exists
-        if (GameObject.FindGameObjectWithTag("SceneManager") != null) {
-            Destroy(this.gameObject);
-        } else { // if it doesn't, then this is the only one
-            this.gameObject.tag = "SceneManager";
+    void Awake()
+    {
+        if (Instance == null)
+        {
+            Instance = this;
         }
+        // Make this object stay around when switching scenes
         DontDestroyOnLoad(this.gameObject);
         SceneManager.sceneLoaded += OnSceneLoaded;
     }
 
-    void OnSceneLoaded(Scene scene, LoadSceneMode mode) {
+    void OnSceneLoaded(Scene scene, LoadSceneMode mode)
+    {
         GameObject pauseMenu = GameObject.Find("PauseMenuCanvas");
-        if (pauseMenu != null) {
+        if (pauseMenu != null)
+        {
             Button quitButton = GameObject.Find("QuitButton").GetComponent<Button>();
             quitButton.onClick.AddListener(BackToMainMenu);
         }
-        if (scene.buildIndex == 0) { // if this is the menu
+        if (scene.buildIndex == 0)
+        { // if this is the menu
             GameObject.Find("NewGameButton").GetComponent<Button>().onClick.AddListener(NextScene);
         }
     }
 
-    public void NextScene() {
+    public void NextScene()
+    {
         SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex + 1);
     }
 
-    public void BackToMainMenu() {
+    public void BackToMainMenu()
+    {
         SceneManager.LoadScene(0); // main menu scene should be 0
     }
 
-    public void LoadChosenScene(int index) {
+    public void LoadChosenScene(int index)
+    {
         SceneManager.LoadScene(index);
     }