tidy up level manager related scripts

scripts were not classified

created a LevelManager folder in the scripts folder

Assets/Scripts/LevelManager.meta

@@ -0,0 +1,8 @@
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Assets/Scripts/Singleton.cs

@@ -1,4 +1,8 @@
-public class Singleton<T> where T : Singleton<T>, new()
+/// <summary>
+/// this class is not a MonoBehaviour. Its purpose is to make it possible to have global classes that will not be in the scene.
+/// </summary>
+/// <typeparam name="T"></typeparam>
+public class Singleton<T> where T : Singleton<T>, new()
 {
     private static T _instance;
     public static T Instance

Assets/Scripts/Tiles.meta

@@ -0,0 +1,8 @@
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