tgstation.dmm fixes

Closes https://github.com/d3athrow/vgstation13/issues/1328
Closes https://github.com/d3athrow/vgstation13/issues/1415
Closes https://github.com/d3athrow/vgstation13/issues/1450
Closes https://github.com/d3athrow/vgstation13/issues/1489

Daily reminder to update the changelog :^)
Merge pull request #1518 from Duny-/map_issues

tgstation.dmm fixes