* wl-summary.el (wl-summary-buffer-unsync-mark-number-list): New

* wl-summary.el (wl-summary-buffer-unsync-mark-number-list): New
internal variable (buffer local).
(wl-summary-window-scroll-functions): New function.
(wl-summary-mode): Use it insteaf of wl-summary-lazy-highlight.
(wl-summary-rescan): Set wl-summary-buffer-unsync-mark-number-list
as nil.
(wl-summary-update-status-marks): Added arguments beg, end and
check.
(wl-summary-update-mark-window): Use function.
(wl-summary-sync-update): Follow the change above.
(wl-summary-switch-to-clone-buffer): Copy
wl-summary-buffer-unsync-mark-number-list.
(wl-summary-goto-folder-subr): Set
wl-summary-buffer-unsync-mark-number-list and
use wl-summary-window-scroll-functions insteaf of
wl-summary-lazy-highlight.

* wl-vars.el (wl-summary-lazy-update-mark): New user option.