* riece-button.el (riece-button-insinuate): Buttonize channel buffers.

* riece-history.el (riece-channel-list-history-face): New face.
(riece-history-format-channel-list-line): New function.
(riece-history-insinuate): Add ?+ to
riece-channel-list-mark-face-alist; add
riece-history-format-channel-list-line to
riece-format-channel-list-line-functions.

* riece-highlight.el (riece-channel-list-current-face): Arrange colors.