Return number of channel participants in disco#info, if known
When doing a disco#info query on an IRC channel, it would be great to obtain/return the
muc#roominfo_occupants item with the number of people in the channel.
If the user is already logged in to the IRC channel with another (MSN) client, that list should be available already. Otherwise, it might be useful to do a /LIST to query the server for topic and number of participants.