Create Delete Layer functions in Scenes

[nhurde]

2 functions

1 should take in the scene pointer, while the other can take in the scene id.

It should also have a 2nd parameter to determine if the contents of the layer are deleted altogether(default) or if the contents are transferred over to a 3rd parameter or next available layer.

This function is most likely to be rarely called as currently no game logic will need to individually delete scenes, but mayhaps someone customizing engine will find it useful.