Added chanlimit setting in yaircd.conf, and updated the code in serverinfo to deal with it. Added channels list to the client's structure, and initialized it in create_client().
Channel listing in each client is now implemented and tested.
Refactored channel.c part() functions into a generic function to make it easier to implement QUIT.
Implemented quit. Quit message is still hardcoded.
Added some missing documentation in the new functions that deal with QUIT.