(easy-menu-define): Doc fix.

(easy-menu-define): Doc fix.
(easy-menu-create-menu): New keyword :included.
(easy-menu-do-add-item): New keyword :included.  SUFFIX may
be an expression, not only a string.  Simulate style `button'.
Use easy-menu-define-key-intern instead of easy-menu-define-key.
(easy-menu-define-key-intern): New function.
(easy-menu-add-item): Understand value returned from
easy-menu-item-present-p and easy-menu-remove-item.
(easy-menu-return-item): New function.
(easy-menu-item-present-p, easy-menu-remove-item): Use it.