Manually initialize TimerManager

[Petethegoat]

Some objects were not cleaned up when closing the scene. (Did you spawn new GameObjects from OnDestroy?)
The following scene GameObjects were found:
TimerManager

If the first time a timer is registered is in the OnDisable or OnDestroy function, then it may create the TimerManager as a scene is closed (for example, when exiting playmode)

I simply added a method to initialize it manually. This could also use RuntimeInitializeOnLoadMethod and occur with no user action required.

 /// <summary>
 /// Initializes the TimerManager, useful if your first Timer usage
 /// may otherwise be in OnDisable or OnDestroy, which may be called when exiting playmode.
 /// </summary>
 public static void InitializeManager()
	{
 if(Timer._manager == null)
 {
 TimerManager managerInScene = Object.FindObjectOfType<TimerManager>();
 if(managerInScene != null)
 {
 Timer._manager = managerInScene;
 }
 else
 {
 GameObject managerObject = new GameObject { name = "TimerManager" };
 Timer._manager = managerObject.AddComponent<TimerManager>();
 GameObject.DontDestroyOnLoad(managerObject);
 }
 }
 }