Implement a 'remove()' method to PhysicsCollisionCategories.as

[Snky]

Why? The limitation of the max number of categories(can the max number be raised?). With this feature, a scene could load the required categories, and unload them when the scene ends; Thus allowing at least fifteen categories minimum per scene rather than per application.

[gsynuh]

@Snky I didn't test it in a state but separately, so it seems all good but let me know if there are any issues :)