Update copyright and commentary.

Update copyright and commentary.
(easy-mmode-define-toggle): Deprecate the use of *-(on|off)-hook.
Print a status message if the toggle is called interactively.
(define-minor-mode): Allow INIT-VALUE to be (global . INIT-VALUE)
for global minor modes and use `defcustom' for them.
Use add-minor-mode.
(easy-mmode-define-derived-mode): Remove.
(define-derived-mode): Fancier default docstring.
(easy-mmode-define-navigation): Signal an error rather than (ding).