* wl-folder.el (wl-folder-buffer-group-p): Rewritten.

* wl-folder.el (wl-folder-buffer-group-p): Rewritten.
(wl-folder-put-folder-property): New function to put text property.
(wl-folder-jump-to-current-entity, wl-folder-entity-assign-id)
(wl-folder-insert-entity, wl-folder-update-diff-line)
(wl-folder-update-diff-line, wl-folder-pick): Change accordingly.
* wl-e21.el, wl-xmas.el, wl-mule.el
(wl-highlight-folder-current-line): Ditto.
* wl-fldmgr.el (wl-fldmgr-get-path-from-buffer, wl-fldmgr-cut)
(wl-fldmgr-copy-region, wl-fldmgr-copy, wl-fldmgr-delete)
(wl-fldmgr-rename, wl-fldmgr-sort, wl-fldmgr-unsubscribe)
(wl-fldmgr-access-display-all, wl-fldmgr-set-petname): Ditto.