* wl-mime.el (wl-mime-display-text/plain): New function.

* wl-mime.el (wl-mime-display-text/plain): New function.
(wl-mime-display-header): Ditto.
(wl-mime-setup): Register `wl-mime-display-text/plain' as a
body-presentation-method for text/plain;
Register `wl-mime-display-header' as a header-presentation-method;
Don't set up `elmo-message-text-content-inserted-hook' and
`elmo-message-header-inserted-hook'.

* wl-message.el (wl-message-buffer-all-header-flag): New buffer local
variable.
(wl-message-display-internal): Set `wl-message-buffer-all-header-flag'
as t if flag is 'all-header;
Don't bind `elmo-message-ignored-field-list',
`elmo-message-visible-field-list' and `elmo-message-sorted-field-list'.