(global-cwarn-mode): Use easy-mmode-define-global-mode.
(cwarn-font-lock-keywords): New function.
Replaces cwarn-font-lock-remove-keywords cwarn-font-lock-add-keywords.
(cwarn-font-lock-match): New macro.
(cwarn-font-lock-match-assignment-in-expression)
(cwarn-font-lock-match-dangerous-semicolon)
(cwarn-font-lock-match-reference): Use it.
Add shift-assignment operators to those highlighted, and highlight
the whole operator rather than just the "=". From Broadey Kevin
<Kevin.Broadey@motorola.com>.
(global-cwarn-mode): Don't make it a user option. Unquote lambda.
(cwarn-font-lock-feature-keywords-alist): Don't make it a user
option. Provide :type.
(cwarn-configuration): Provide :type.
(cwarn-mode): Doc fix.