* riece-ctlseq.el (riece-ctlseq-scan-region): Abolish.

(riece-ctlseq-requires): New function.
(riece-ctlseq-message-filter): Assume the existence of
riece-put-overlay-faces, add 'riece-overlay-face property.

* riece-keyword.el (riece-keyword-scan-region): Abolish.
(riece-keyword-message-filter): Assume the existence of
riece-put-overlay-faces, add 'riece-overlay-face property.

* riece-highlight.el (riece-put-overlay-faces): New function.
(riece-highlight-insinuate): Add riece-put-overlay-faces to
riece-after-insert-functions.