uranusmail: move the date_format to the config section in .notmuch-config
main: extract the code rendering a thread line into it's own method
Merge branch 'master' into list_buffers

* master:
  main: extract the code rendering a thread line into it's own method
  uranusmail: move the date_format to the config section in .notmuch-config

Conflicts:
	plugin/uranusmail.vim
thread: for each thread create a MailThread to query it directly
buffer_list: show the thread info for a buffer