* wl-vars.el (wl-draft-forward-hook): Setup to put forwarded flag.

* wl-vars.el (wl-draft-forward-hook): Setup to put forwarded flag.
(wl-summary-persistent-mark-priority-list): Add `forwarded'.
(wl-summary-uncached-mark): Renamed from wl-summary-read-uncached-mark.
(wl-summary-new-cached-mark): Changed default value to 'n'.
(wl-summary-unread-cached-mark): Changed default value to 'u'.
(wl-summary-answered-cached-mark): Changed default value to 'a'.
(wl-folder-sync-range-alist): Remove spec for 'flag.
(wl-summary-force-prefetch-folder-list): New user option.

* wl-summary.el (wl-summary-mode-map): Bind 'M-k' to
`wl-summary-toggle-persistent-mark'.
(wl-summary-update-mark-and-highlight-window): Don't highlight when
number is nil.
(wl-summary-mark-as-answered-region): Set interactive argument of
`wl-summary-set-persistent-mark-internal'.
(wl-summary-mark-as-important-region): Ditto.
(wl-summary-unset-persistent-mark): Ditto.
(wl-summary-set-persistent-mark): Ditto.
(wl-summary-mark-as-answered): Ditto.
(wl-summary-mark-as-important): Ditto.
(wl-summary-set-persistent-mark-internal): Do nothing
when `elmo-message-flag-available-p' is nil.
(wl-summary-toggle-persistent-mark): New function.
(wl-summary-goto-folder-subr): Call `wl-summary-force-prefetch'
when the folder matches `wl-summary-force-prefetch-folder-list'.

* wl-highlight.el (wl-highlight-summary-current-line): Do nothing
when number is nil.
(wl-highlight-summary-forwarded-face): New face.