HN: ShowHN items in Frontpage por Bg Dam

With the growth of HN in recent years, and too few people looking at /newest and /shownew, a lot of good posts, esp. 'Show HNs' disappear in the crowd.

This extension picks 5 (customizable) random items from /newest and /shownew (or any one, customizable), and appends them to the top of the frontpage (and it's next pages).