Added Z-level support.
Added Z-level support for ZAS, disabled by default to save CPU.
- Use #define ZLEVELS or uncomment it in _docs.dm to turn it on.
Fixed a special case with simulated turfs being replaced by space.
Actually any unsimulated turf, but mostly space.
Fixed some zone.remove() bugs:
Turf should be set back to no gas overlays.
Debug mode checks if zone actually contains turf
(might be useful in turf replacement.)
Fixed some weird bugs concerning space and the creation thereof.
Added documentation, split ConnectionManager.dm, removed some unused procs.
Added a proc to find the other zone in an edge for future procs.
Fixed the stupid .int again.
Fixed some debug verbs, removed ZASDBG define.
baystation12.int is the worst thing to happen to version control
Zones didn't split when a full window was placed.
Fixed walls not splitting zones.
Added code protecting against obscure merges of invalid zones.
 - Usually happened when welding fuel tanks caused secondary explosions.
Removed a leftover generally-accessible debug verb.
Added Reboot ZAS as a debug verb.
 Replaces the air controller, marks all old zones invalid,
 and adds every turf to the update list. Results are the same as on a
 server start.
Merge pull request #4466 from Aryn/master

New ZAS Bugfixes