Prevent replying to self in locked topics

I think it's time to refactor the ACL methods.

tildes/tildes/models/comment/comment.py

@@ -170,6 +170,7 @@ class Comment(DatabaseModel):
             acl.append((Allow, 'admin', 'view'))
 
             acl.append((Allow, self.user_id, 'view'))
+            if not self.topic.is_locked:
                 acl.append((Allow, self.user_id, 'reply'))
             acl.append((Allow, self.user_id, 'edit'))
             acl.append((Allow, self.user_id, 'delete'))