Refactored random map generator system and added several terrain generators.

Created a global list to track base turfs for explosions/shuttle moves.
Remaps the asteroid to be a moonlet. Tidies up some references to 'asteroid', removes moonbase from the accessible z level list.

code/game/objects/items/stacks/tiles/plasteel.dm

@@ -26,28 +26,9 @@
 	stacktype = /obj/item/stack/tile/plasteel
 	build_type = /obj/item/stack/tile/plasteel
 
-/*
-/obj/item/stack/tile/plasteel/attack_self(mob/user as mob)
-	if (usr.stat)
-		return
-	var/T = user.loc
-	if (!( istype(T, /turf) ))
-		user << "\red You must be on the ground!"
-		return
-	if (!( istype(T, /turf/space) ))
-		user << "\red You cannot build on or repair this turf!"
-		return
-	src.build(T)
-	src.add_fingerprint(user)
-	use(1)
-	return
-*/
-
 /obj/item/stack/tile/plasteel/proc/build(turf/S as turf)
 	if (istype(S,/turf/space))
 		S.ChangeTurf(/turf/simulated/floor/plating/airless)
 	else
 		S.ChangeTurf(/turf/simulated/floor/plating)
-//	var/turf/simulated/floor/W = S.ReplaceWithFloor()
-//	W.make_plating()
 	return