Removed update_values(). RIP, shine on you CPU diamond.
Removed get_moles_by_id and get_archived_moles_by_id, all moles are now accessed directly to reduce call cost.
Added set_temperature and set_volume procs which recalc pressure when temperature or pressure change.
Heat_capacity is now a var updated when gases update.
Modified adjust_gas to use set_gas, modified set_gas to alter heat_capacity, total_moles, and pressure as needed.
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.
