#469350 by Berdir, nbz | frankcarey, Plazmus: Added UI Improvements: Move secondary tabs to primary tabs.

#575444 by Berdir: Several improvements needed for other modules (forward, recipient_list, realname integration)

#444682 by Berdir: Performance improvement: Remove user_load() from thread_load() in favor of single sql join to users table

#405240 by nbz, Berdir: Messages now have #new anchors that jump user to new messages. Use SUM instead of COUNT for is_new in the list messages query.

#376005 by Berdir: API change: _privatemsg_send returns more granular information about success or failure of sending a message as well as improved other API to make use of this

#490650 by litwol, JirkaRybka, nbz, Berdir, Liam McDermott: Message to oneself AND aditional recipients remains as unread forever. This patch fixes this behavior moving forward as well as providing update hook to update old messages that were affected by this issue.

#441042 by Berdir: Replace multi-select list of users in filter form with a more performant autocomplete-text-field

#404960 by Berdir: messages/view/% shows the participants of a conversation even if there are no messages that the user can view.