* riece-unread.el: Require 'riece-highlight when compiling.

* riece-unread.el: Require 'riece-highlight when compiling.
(riece-unread): New custom group.
(riece-channel-list-unread-face): New variable.
(riece-channel-list-unread-face): New face.
(riece-unread-requires): New function.
(riece-unread-insinuate): Add ?! to riece-channel-list-mark-face-alist.

* riece-highlight.el: Highlight *Channels* buffer; rename
riece-*-face -> riece-dialogue-*-face, riece-highlight-* ->
riece-dialogue-*.
(riece-channel-list-font-lock-keywords): New variable.
(riece-channel-list-mark-face-alist): New variable.