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/admin/topic.dm

@@ -2077,7 +2077,7 @@
 						if(F.z == 1)
 							F.name = initial(F.name)
 							F.desc = initial(F.desc)
-							F.overlays = null
+							F.overlays.Cut()
 							F.lava = 0
 							F.update_icon()
 					floorIsLava = 0