atmos changes; sleepy edges and hardy rwalls

Zone and unsimulated edges will now sleep and suspend processing when the two sides become approximately equal.
Airless turfs are now actually airless and space is the right temperature again.
r-walls now have a lot more health and the fire damage scaling for walls has been reworked to scale better at high temperatures.

zas is still buggy and slow in some cases, that'll need more work.
overlay issue is still in, can't figure out what causes it.