Z-Level Compatibility

Now possible to configure 3 different kind of Z-levels.
Station levels: Which Z-levels the station exists on.
Contact levels: Which Z-levels are typically affected by, for example, Code Red which alters the visual state of fire alarms.
Player levels: Which Z-levels a character can typically reach.
Merge pull request #6891 from PsiOmegaDelta/Z

Multi Z-Level Compatibility