- Remove "channels" menu and instead list group chats in the roster view
- Allow joining a group chat by double ckicking on it in the roster
- Support for bookmarks2 (XEP-0402). XEP-0048 is also implemented, but
currently disabled.
- Joining a group chat adds it to the bookmarks with autojoin enabled,
unless it is not an user initiated action (for example, someone else
invited you in a room)
- Leaving a groupchat adds it to the bootkmarks, with autojoin disabled
(so you can easily access the server-side history for it or join back)
- Bookmarks can be deleted by right click->remove in the Roster.
Fixes #32, #40