#123 Topic Reminder

[Si]

When the Calendar feature is complete
(http://sourceforge.net/tracker/index.php?func=detail&aid=1587021&group_id=152364&atid=784892),
need to add a topic reminder feature.

This feature would allow registered users to add a
reminder about a topic/post for future action.

The user would be sent an email on the due date with a
link to the topic/post that they wanted reminding about.