for(var/bad_code in world)

Removes a very large amount of world loops.
Adds a macro to painlessly generate a global list, and the needed code to modify the list when an object is made or deleted automatically.
Cleans up some commented out code.

code/modules/lighting/lighting_setup.dm

@@ -1,6 +1,6 @@
 // Create lighting overlays on all turfs with dynamic lighting in areas with dynamic lighting.
 /proc/create_all_lighting_overlays()
-	for(var/area/A in world)
+	for(var/area/A in all_areas)
 		if(!A.dynamic_lighting)
 			continue
 		for(var/turf/T in A)