Adds canbreathe var to tanks, internals button will not connect you to internals tanks with canbreathe = 0
Fixes lack of mask check. Updates the span messages to remove "breathing from your the emergency oxygen tank"
Adds canbreathe = 0 to carbon dioxide jetpacks.
Merge pull request #827 from Dorsisdwarf/breathcode

Updates internals button, removes breathing from plasma tanks.