Fire update.  Should now burn out after a time, and temperature varies on a number of conditions.  Fixed a runtime, and made fire work in canisters.  Ingame modification of ZAS is now possible again.  Firedoors now remove duplicate firedoors on the same turf.
Napalm can now be made, due to fire changes.
fuel is now a bit less derpy.  Napalm produces volatile fuel, and less of it.  Fire consumes more welding fuel.
Compile fix.
Merge pull request #2652 from SkyMarshal/master

Fire fixes and improvements.  Note: May need fine tuning.