Functionality to deactivate buttons via signals

[Deconimus]

See Issue #17

As of now, this would enable to deactivate buttons for "escape hatch" cutscenes in Chamber04, Chamber13 and Chamber14.

In those chambers, the relevant button objects in the blender files would simply need to be renamed to something like:

@button open_door open_door_cube escape_hatch

(At the example of the button in chamber14).