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/unused/pda2/base_os.dm

@@ -95,7 +95,7 @@
 				if(2)
 					//Messenger.  Uses Radio.  Is a messenger.
 					//TO-DO: ~file sharing~
-					src.master.overlays = null //Remove existing alerts
+					src.master.overlays.Cut() //Remove existing alerts
 					dat += "<h4>SpaceMessenger V4.0.5</h4>"
 
 					if (!src.message_mode)

code/unused/pda2/pda2.dm

@@ -253,7 +253,7 @@
 			for (var/mob/O in hearers(3, src.loc))
 				O.show_message(text("\icon[src] *[alert_message]*"))
 
-		src.overlays = null
+		src.overlays.Cut()
 		src.overlays += image('icons/obj/pda.dmi', "pda-r")
 		return