New site blocks

I've created a couple of new blocks to help with site navigation:

On the news page there is now a 'Recently updated' block on the right showing all new and changed pages (not just those important enough to show up in the main page). As well as letting you see all new stuff (stories, comments and pages) in one place, this allows us to simplify the main site menu, by removing the need for the 'recent posts' item.

Also, on the software index, the 'Recents comments' block is replaced by 'Popular software' (sorted by total page views).