[Telepathy] Proposed change to group channels as used for chatrooms

[Simon McVittie]

Somewhat related to my mail about renaming: At the moment, with Gabble,
it'd be very hard for us to implement changing your nick on entry to a room,
because RequestChannel automatically makes you join the channel, so room
members always would see the default nick at least momentarily.

Rob McQueen suggested an ingenious solution: have RequestChannel put
your self-handle into LocalPending (while gathering as much information
about the channel as the CM can without actually joining it), so the client
can set your nick (by whatever mechanism we decide is appropriate); then
call AddMembers to move your self-handle from LocalPending to Members (which
would actually join the channel).

(Rob: do you still think we should go ahead with this change? I think
it's a nice design.)

This would require the following change to all Telepathy clients wishing
to be forwards-compatible:

If while trying to join a group you find that the self-handle is in
LocalPending state, call AddMembers on it to move it to Members. (This
is the same mechanism as approving someone else's request to join the
group - obviously you should always approve requests from yourself!).

Obviously, a more advanced client would do things like setting the nick
before it called AddMembers, but the above is the minimum needed to be
compatible if we were to implement this Gabble change.

	Simon