* Can query blog posts by multiple tags now.
* e.g. /tagged/blog,updates,-photos would query all posts that have tags
"blog" OR "updates" but NOT show any post with tag "photos"
* Legacy-importer tool updates the DB primary key serial after migrating
the posts, to be max(posts.id)+1 -- especially important for
PostgreSQL and MySQL (SQLite3 correctly picked the next ID by
default?)
* Add blog archive page and RSS, Atom and JSON feeds for the blog.
URLs are /blog.rss, /blog.atom and /blog.json
* List comments on a post
* Add comments, with preview
* Users can edit their own comments (EditToken)
* Admin can edit all comments
* Delete comments
* Comment counts on main blog index pages
