Add "Fix air" proc

[SirRichardFrancis]

About The Pull Request

Added a way for admins to unfuck the atmos.

Why It's Good For The Game

Sometimes it's nice to have an option like that. Also Jeff requested it.

Testing

Flooded hallways with plasma. Watched it all burn for a moment. Pressed "Fix air" button. Observed plasma fires disappear and air alarms clearing.

Changelog

:cl: admin: Added "Fix air" button to "Admin" tab /:cl: