Add default forum views

I think (imho) that Adv_forum can integrate three default views, adding links in the top of forum list.

Nodes with no replies (table view, fields: node title/link with author, date and forum taxonomy, replies, visits and last post)
Last posts (same as above)
Active threads (same as above)

Example
Thread || Replies || Visits || Last message
thread-icon || Title ||2 || 50 || by Author
-|| by Author today, 5:59 in Forum || || || today, 5:59

Though "last post" and "replies" are useless fields in the first view, it preservers coherence.