Merge remote-tracking branch 'upstream/dev-freeze' into dev

Conflicts:
	code/modules/admin/admin.dm
	code/modules/admin/topic.dm

code/_helpers/lists.dm

@@ -71,11 +71,17 @@ proc/isemptylist(list/list)
 			return 1
 	return 0
 
-//Empties the list by setting the length to 0. Hopefully the elements get garbage collected
-proc/clearlist(list/list)
-	if(istype(list))
-		list.len = 0
-	return
+/proc/instances_of_type_in_list(var/atom/A, var/list/L)
+	var/instances = 0
+	for(var/type in L)
+		if(istype(A, type))
+			instances++
+	return instances
+
+//Empties the list by .Cut(). Setting lenght = 0 has been confirmed to leak references.
+proc/clearlist(var/list/L)
+	if(islist(L))
+		L.Cut()
 
 //Removes any null entries from the list
 proc/listclearnulls(list/list)