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/modules/power/singularity/collector.dm

@@ -129,7 +129,7 @@ var/global/list/rad_collectors = list()
 
 
 /obj/machinery/power/rad_collector/proc/update_icons()
-	overlays = null
+	overlays.Cut()
 	if(P)
 		overlays += image('icons/obj/singularity.dmi', "ptank")
 	if(stat & (NOPOWER|BROKEN))

code/modules/power/singularity/field_generator.dm

@@ -34,7 +34,7 @@ field_generator power level display
 
 
 /obj/machinery/field_generator/update_icon()
-	overlays = null
+	overlays.Cut()
 	if(!active)
 		if(warming_up)
 			overlays += "+a[warming_up]"