Border firelock changes

Created by: ComicIronic

This is how I plan to solve #2161 (closed).

Now with a flashy new sprite I cobbled together out of bits of other sprites! Fixed their bizarre air behaviour that was causing ZAS issues - air groups in any direction were being blocked. A border firelock reads off its own turf for the direction opposite the one it faces. Two border firelocks on a turf will no longer cause one to delete itself. getCardinalAirInfo is now passed a source atom. Moved firedoor overlays into a global list system because new icons were being spawned every process(). EXAMPLES: webm: http://puu.sh/i5eWq/2531690103.webm Image

Ministation needed a reformat for some reason, so that's why its line change number is so big.