UrlParser: support subdomains in get_subreddit
Domain area: add new user pref to show extra info

If enabled, shows additional info in the domain text when it's
available. Initially, this includes the source subreddit for internal
reddit links, and anywhere that the media_author_url or
media_author_name info is available through embed.ly (such as YouTube
channels, Twitter authors, etc.)
r.utils.pyStrFormat: Replace more than one format parameter.
Flair toggle: Add a <label> tag