Adds 7th z level to metastation and fixes piping.

Amazed the map merger survived that, honestly.
Fixes #5649
Fixes #5710

Gonna go fix #5709 one moment.
Fixes #5709.
Removes extinguisher from singulo area and replaces floors in the PA area with plating.
Ditto for metastation.
Changed products in vending machine in syndie base.
Ditto on boxstation.
Adds ventilation to incinerator.
Merge pull request #5711 from WJohn/mapfixestwo

Adds 7th z level to metastation and fixes piping.