libsaria: Remove old walk_queue() function

I've replaced it with a more generic function that should be able to
handle the library and playlist, too (yay for code reuse!).

libsaria/sources/queue/__init__.py

@@ -12,12 +12,6 @@ add_ids = queue.add_ids
 rm_ids  = queue.rm_ids
 reset   = queue.reset
 
-def walk_queue(*attrs):
-	res = []
-	for id in queue.queue_list:
-		res.append(library.get_attrs(id, *attrs))
-	return res
-
 def list():
 	for id in queue.queue_list:
 		yield id