Feedback Admin Panel Stuff

- Renamed parent_link to get_parent_link
- Added get_avatar_comment_types filter to register class
- Cleaned up column_author method a bunch of table class
- Set show_in_admin_all_list to FALSE for feedback comment status
- Feedback can be trashed without being redirect to the comments page when editing an individual comment.
- Lots of simplification and cleanup of the column_comment method.