Remove some world loops (#2965)

changes:

Replaces a lot of in-world loops with more specific lists.
Recipes are now copied in SSmachinery/Recover()
Fixed bad sorting on all_areas list.
Added skeleton Destroy() to SMESes as they did not have one and are failing to GC.
Seems to shorten SSatoms init a bit, maybe from removal of in-world in MULEs?

code/modules/admin/secrets/fun_secrets/fix_all_lights.dm

@@ -6,5 +6,5 @@
 	if(!.)
 		return
 
-	for(var/obj/machinery/light/L in world)
+	for(var/obj/machinery/light/L in machines)
 		L.fix()

code/modules/admin/secrets/random_events/gravity.dm

@@ -16,7 +16,7 @@
 		return
 
 	gravity_is_on = !gravity_is_on
-	for(var/area/A in world)
+	for(var/area/A in all_areas)
 		A.gravitychange(gravity_is_on,A)
 
 	feedback_inc("admin_secrets_fun_used",1)