Adds a custom category for link list items and provides options for excluding them from the previous and next links as on Daring Fireball
Moves custom category description and deletion text to two constants.
Adhering to WordPress coding standards
Disables use of custom category when the custom category is deleted by an admin.
Filters the custom category slug of any non-printable characters so that it will not interfere with friendly URLs.
Update to prev/next link exclusion
Encodes star glyphs
Updated version 2.9 info