* liece-commands.el (liece-command-beep): New function.

Toggle the automatic beep notice when the channel message is received.

* liece-handle.el (liece-handle-privmsg-message): added it.

* liece-misc.el (liece-beep): New function.

* liece-vars.el (liece-default-beep): New variable.
(liece-beep-when-invited): Ditto.
(liece-beep-when-privmsg):  Ditto.
(liece-beep-words-list): Ditto.

* liece.el (liece-dialogue-mode-map): Bind "\C-B" to liece-dialogue-beep.