Adds this Game Object to the Update List belonging to the Scene.
When a Game Object is added to the Update List it will have its preUpdate method called
every game frame. This method is passed two parameters: delta and time.
If you wish to run your own logic within preUpdate then you should always call
preUpdate.super(delta, time) within it, or it may fail to process required operations,
such as Sprite animations.
This Game Object.