Evens out space lighting and prevents space fire/party alarms

Adds a dedicated lighting subarea for space turfs, and forces all space turfs to use it.  This evens out irregularities in lighting space turfs ("this empty space is slightly brighter than that empty space") and removes fire and party alarms from space tiles.

For now I have also made space lighting subareas unpowered.  I guess this operates on the theory that the tiles mysteriously teleport power between themselves (along with flashing red lights and party strobes) but it does not work on empty space.