Moved gas_mixture gas numbers to a list which is connected to a global gas_datum list, like with reagents.
Modified some maths procs to be more sane, added adjust_gas and set_gas to help with processing.
Added a modular system for gas flags - gases can now be marked as fuel and oxidiser with a flag, logged with a flag, scanned with a flag, etc.
Changed scrubbers to use a list of scrubbing gases rather than a set of vars.
Made miners and xenoarch effects more sensible - they now produce gas by ID, not manually.
Made turfs' starting gases into a list, removed turf gas number vars.
Adds registers to the AAC, these are simply variables.
By default, 10 registers max, this is, however, softcoded.
Data can be both set and gotten from registers using automations.
+ Now with code import/export (JSON-based)
* Remove script works now
* Correctly interfaces with digital valves
* Yes/No dialogs are less stupid now
* Vents stay on after being disconnected from pipenet.
* Valves no longer removed from machinery list.
* JSON parser fixes.
- Atmospherics Automation Consoles now have their own board to ensure
they turn back into the right computer when deconstructed
- While at it, made the new board constructible
