Library get_attr values

We should walk the tag values bacwards, rather than using the normal
walk_backwards function.

libsaria/collection/library.py

@@ -91,7 +91,7 @@ def get_attrs(id, *attrs):
 		return [0] * len(attrs)
 
 	get  = rec.__dict__.get
-	tags = rec.tags.walk_backwards()
+	tags = rec.tags.walk_vals_backwards()
 	for attr in attrs:
 		if attr == "id":
 			res += [id]