Old-Centcom-inspired Away Mission!

By popular demand, adds a centcom-inspired away map; featuring thunderdome, grand court, and kitchen arena.
Makes centcom-style doors not opaque.
Removes Pete's old WIP arctic map

Adds helpful notes to the fileList.txt so SOOOOOMEEEEEEBOOOOOOODYYYY doesn't compile all the maps onto the server at once.
Sets the .dme to include the away map code files.
Merge branch 'master' of https://github.com/tgstation/-tg-station
Merge pull request #1551 from Cheridan/AwayMaps

Old-Centcom-inspired Away Mission!