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/game/machinery/computer3/computers/crew.dm

@@ -57,7 +57,7 @@
 
 
 	proc/scan()
-		for(var/obj/item/clothing/under/C in world)
+		for(var/obj/item/clothing/under/C in all_clothing)
 			if((C.has_sensor) && (istype(C.loc, /mob/living/carbon/human)))
 				tracked |= C
 		return 1

code/game/machinery/computer3/computers/medical.dm

@@ -128,7 +128,7 @@
 						dat += "<a href='?src=\ref[src];screen=1'>Back</a>"
 						dat += "<br><b>Medical Robots:</b>"
 						var/bdat = null
-						for(var/mob/living/bot/medbot/M in world)
+						for(var/mob/living/bot/medbot/M in mob_list)
 
 							if(M.z != computer.z)	continue	//only find medibots on the same z-level as the computer
 							var/turf/bl = get_turf(M)

code/game/machinery/computer3/computers/prisoner.dm

@@ -27,7 +27,7 @@
 		else if(screen == 1)
 			dat += "<HR>Chemical Implants<BR>"
 			var/turf/Tr = null
-			for(var/obj/item/weapon/implant/chem/C in world)
+			for(var/obj/item/weapon/implant/chem/C in all_chem_implants)
 				Tr = get_turf(C)
 				if((Tr) && (Tr.z != computer.z))	continue//Out of range
 				if(!C.implanted) continue
@@ -37,7 +37,7 @@
 				dat += "<A href='?src=\ref[src];inject10=\ref[C]'>(<font color=red>(10)</font>)</A><BR>"
 				dat += "********************************<BR>"
 			dat += "<HR>Tracking Implants<BR>"
-			for(var/obj/item/weapon/implant/tracking/T in world)
+			for(var/obj/item/weapon/implant/tracking/T in all_tracking_implants)
 				Tr = get_turf(T)
 				if((Tr) && (Tr.z != computer.z))	continue//Out of range
 				if(!T.implanted) continue