Log Message:
Update riece to 3.0.0.

* Major changes in 3.0.0

** Changed the meaning of riece-username.  If you set this option, you
   will need to set riece-realname instead. (ueno)

** Cause an error if a user requests to close already closed server. (yoichi)

** New add-on riece-epg.el, which enables secure conversation using
   GnuPG. (ueno)

** Fixed a couple of bugs in inviting users. (Steve Youngs)

** Fixed a redisplay bug when a user leaves a channel. (ueno)

** Reverted the default value of riece-alias-alternate-separator to
   "@". (ueno)