* TODO add notification system server-side and to the client
  it should allow users on the tilde to subscribe to a mailing list for
selected threads, and the api should allow for event listings per thread
when given a certain time (kind of like `message_feed`)
* TODO Author-only "announcement" threads
* TODO HTML output from the formatter
* TODO integrate thread pins to urwid client
* TODO add search highlights to in-thread searching
