Animated Avatars, Emoji Nicks, Hats, Related Chats

* Support animated avatars
* Allow any character (especially any emoji) in nicknames used in a channel
* Show "hats" in list of channel participants
* Option to explore related channels from channel details
* Make contact sync more reliable with multiple accounts
* Fix per-account colours in New Conversation activity
* Allow IQs to timeout (and use this for commands)
* Reply to null thread won't trigger a new thread in 1:1
* Better Jabber ID validation
* Many bugfixes