Some turf cleanup and the like. Trace gases are now properly handled by ZAS on world load.

Fixes #2485

Conflicts:
	code/game/turfs/simulated/floor_types.dm

code/ATMOSPHERICS/datum_pipeline.dm

@@ -149,10 +149,6 @@ datum/pipeline
 			air.merge(air_sample)
 			//turf_air already modified by equalize_gases()
 
-		if(istype(target) && !target.processing)
-			if(target.air)
-				if(target.air.check_tile_graphic())
-					target.update_visuals(target.air)
 		if(network)
 			network.update = 1