Fix read-only ghost access.
Make catwalks behave unsimulated.  Still need to make them suck air from surrounding tiles.
Merge branch 'Bleeding-Edge' of github.com:d3athrow/vgstation13 into Bleeding-Edge
Merge branch 'Bleeding-Edge' of github.com:d3athrow/vgstation13 into Bleeding-Edge
Fix github #401: Cloning computer has wrong poweroff icon.
Merge branch 'Bleeding-Edge' of github.com:d3athrow/vgstation13 into Bleeding-Edge