Update docs and fix minor code issue:...Update error messages.
NUM/invite now also accepts ID's (not only public keys).
The title is now also changed for the changer.
Merge branch 'toktok'....This merge updates ratox to toktoks toxcore, which is being developed, and
adds groupchats (although lacking audio group chats at the moment).
Fix warnings....The title of a conference is apparently not known immediately after joining the
conference, so don't print a warning in confcreate(), just wait for the
cbconftitle() callback immediately afterwards.
Friends that are not online can't be invited to conferences, logmsg' in that case.
Print the name of the conference before messages in cbconfmessage().
