Fix handling of Post#edited_at.

It should only be touched when a post is actually updated by its author, so it's now being touched from within PostsController.
Fix timeline seeding of new friends.

When a remote user is polled, only add their posts to the timelines of followers if they've been updated _after_ the friendship was initiated.
Fix timeline batch import order problem by importing polled posts in reverse order. :-)
Improve User#poll! by only going through followings once.
Add unique DB index to posts.guid.

Should have been there from the start, what the heck was I thinking? If you're hosting your own #pants instance and this migration is giving you trouble, you'll need to check your `posts` table for duplicate GUIDs and delete as many rows as necessary (there should only ever be one row per GUID.)

You can identify duplicate posts in your database through the following dumb statement in `rails console`:

    Post.group(:guid).pluck('guid, count(guid)').select { |i| i.last > 1 }
Wrap upserting of posts in a transaction.
Andy is finally friends with Ben.
Implement additional post actions on incoming timeline.

* Hide a post from your incoming timeline
* Hide all incoming posts
* Directly add a user as a friend from your incoming timeline
Change ATOM feed to use actual post titles if available.
Improve styling of headings inside posts.
Strip Post#to_title of whitespace.
Fix post title extraction so blockquotes are ignored.
Fix styling of hashtags within heading tags.
Change hashtag linking so the links are fully qualified.
Change default mobile viewport to 600px
Fix previous viewport.
Don't render incoming posts if none are available.
Fix page titles for Network/Incoming.
Fix page titles again. Then go to bed.