* wl-summary.el (wl-summary-mode-map): Revival of

* wl-summary.el (wl-summary-mode-map): Revival of
wl-summary-mark-as-important related bindings;
Bind 'F','tF','mF','rF','m&'.
(wl-summary-mark-as-important-region): Revival.
(wl-summary-target-mark-mark-as-important): Ditto.
(wl-summary-target-mark-operation): New function.
(wl-summary-target-mark-mark-as-answered): Use it.
(wl-summary-decide-flag): Don't set Important as default.
(wl-summary-mark-as-important-internal): Revival.
(wl-summary-mark-as-important): Ditto.

* wl-thread.el (wl-thread-mark-as-important): Ditto.

* wl-highlight.el (wl-highlight-summary-line-face-spec): Use find-face
instead of facep.