* riece-identity.el (riece-identity-prefix-case-table): Use

* riece-identity.el (riece-identity-prefix-case-table): Use
riece-copy-case-table to define.

* riece-xemacs.el (riece-set-case-syntax-pair): Workaround for
XEmacs 21.1.
(riece-copy-case-table): Ditto.

* riece-emacs.el (riece-copy-case-table): New alias.

* riece-globals.el (riece-channel-regexp): Use
riece-make-interval-regexp to define.
(riece-user-regexp): Ditto.

* riece-compat.el (riece-make-interval-regexp): New function.