Add unread 1.0

Description:

Adds unread to thread title links.

Adds unread to whats-new results pages thread titles, for example the New posts and Latest posts. By adding unread, previously visited threads which have no new posts will go to the latest read post instead of the first post, this is assuming the "Read data marking lifetime" has not expired.

Questions and answers:

Q: Will unread be added if the visitor is not logged in?
A: No, it only be added to logged in members.