More macros (#2955)

changes:

Holomaps now use an area flag instead of a proc to determine which areas do not draw on the holomap.
The supply shuttle once more has a roof.
The supply shuttle's landing zone is now dynamically lit.
Turfs only generate visibility updates on Initialize() after mapload - visualnet is not initialized by then anyways.
Merged /datum/gas_mixture/(init) into /datum/gas_mixture/New().
Converted a ZAS proc into a macro.
Made ZAS attempt to remove a turf from a zone instead of always rebuilding it in a certain case.
Macroized two misc procs.
Fixes #2947.

code/controllers/subsystems/air.dm

@@ -180,7 +180,7 @@ Total Unsimulated Turfs: [world.maxx*world.maxy*world.maxz - simulated_turf_coun
 		var/turf/T = curr_tiles[curr_tiles.len]
 		curr_tiles.len--
 
-		if (QDELETED(T))
+		if (!T)
 			if (no_mc_tick)
 				CHECK_TICK
 			else if (MC_TICK_CHECK)
@@ -304,12 +304,6 @@ Total Unsimulated Turfs: [world.maxx*world.maxy*world.maxz - simulated_turf_coun
 	ATMOS_CANPASS_TURF(., B, A)
 	return ablock | .
 
-/datum/controller/subsystem/air/proc/has_valid_zone(turf/simulated/T)
-	#ifdef ZASDBG
-	ASSERT(istype(T))
-	#endif
-	return istype(T) && T.zone && !T.zone.invalid
-
 /datum/controller/subsystem/air/proc/merge(zone/A, zone/B)
 	#ifdef ZASDBG
 	ASSERT(istype(A))

code/controllers/subsystems/initialization/minimap.dm

@@ -59,7 +59,11 @@
 	for(var/x = 1 to world.maxx)
 		for(var/y = 1 to world.maxy)
 			var/turf/tile = locate(x, y, zlevel)
-			if(tile && tile.loc:holomapAlwaysDraw())
+			var/area/A
+			if(tile)
+				A = tile.loc
+				if (A.flags & HIDE_FROM_HOLOMAP)
+					continue
 				if(IS_ROCK(tile))
 					continue
 				if(IS_OBSTACLE(tile))