## About The Pull Request
Removes all of the duplicate global lists for specific machine types
where the only thing they do is store all machines of that type.
Adds machine tracking to SSmachines in the form of a list for all
machines, and then an associative list for machines by their type.
Previously we have machines in multiple global lists, such as airlocks
being in GLOB.doors, GLOB.airlocks, GLOB.machines.
This makes that not a thing, and also means that iterating through
GLOB.machines looking for a specific type is no longer as expensive.
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