Too remove potential excessive garbage collection per tick. We will be reusing lists for overlays instead of deleting and creating them.

the .Cut() proc on a list will empty a list by default. This also will set the len to 0.

git-svn-id: http://tgstation13.googlecode.com/svn/trunk@5465 316c924e-a436-60f5-8080-3fe189b3f50e

code/FEA/DEBUG_REMOVE_BEFORE_RELEASE.dm

@@ -368,7 +368,7 @@ mob
 				network.marker = rand(1,4)
 
 			for(var/obj/machinery/atmospherics/pipe/P in world)
-				P.overlays = null
+				P.overlays.Cut()
 
 				var/datum/pipe_network/master = P.return_network()
 				if(master)
@@ -378,7 +378,7 @@ mob
 					P.overlays += icon('icons/Testing/atmos_testing.dmi',"marker0")
 
 			for(var/obj/machinery/atmospherics/valve/V in world)
-				V.overlays = null
+				V.overlays.Cut()
 
 				if(V.network_node1)
 					V.overlays += icon('icons/Testing/atmos_testing.dmi',"marker[V.network_node1.marker]")
@@ -396,7 +396,7 @@ turf/simulated
 	verb
 		mark_direction()
 			set src in world
-			overlays = null
+			overlays.Cut()
 			for(var/direction in list(NORTH,SOUTH,EAST,WEST))
 				if(group_border&direction)
 					overlays += icon('icons/Testing/turf_analysis.dmi',"red_arrow",direction)

code/FEA/FEA_turf_tile.dm

@@ -124,7 +124,7 @@ turf
 			super_conduct()
 
 			update_visuals(datum/gas_mixture/model)
-				overlays = null
+				overlays.Cut()
 
 				var/siding_icon_state = return_siding_icon_state()
 				if(siding_icon_state)