* wl-util.el (wl-simple-display-progress): New function.

* wl-util.el (wl-simple-display-progress): New function.
(wl-display-progress-with-gauge): Ditto.
(wl-progress-callback-function): Ditto.

* wl.el (wl-init): Set `elmo-progress-callback-function' as
`wl-progress-callback-function'

* wl-vars.el (wl-display-progress-threshold): New user option.
(wl-display-progress-function): Ditto.

* elmo-util.el (elmo-list-bigger-diff): Abolish.
(elmo-display-progress): Ditto.
(elmo-progress-counter-alist): Ditto.
(elmo-progress-set): Ditto.
(elmo-progress-clear): Ditto.
(elmo-progress-counter-all-value): Rename to
`elmo-progress-counter-total'.
(elmo-progress-counter-format): Rename to
`elmo-progress-counter-action'.
(elmo-progress-counter): New internal variable.
(elmo-progress-callback-function): Ditto.
(elmo-progress-counter-label): New function.
(elmo-progress-counter-set-total): Ditto.
(elmo-progress-counter-set-action): Ditto.
(elmo-progress-call-callback): Ditto.
(elmo-progress-start): Ditto.
(elmo-progress-done): Ditto.
(elmo-progress-notify): Rewrite.
(elmo-with-progress-display): Remove first arguemnt
`condition'. Add optional argument `var' in `spec'.

* elmo-vars.el (elmo-display-progress-threshold): Abolish.
(elmo-display-retrieval-progress-threshold): Ditto.
(elmo-inhibit-display-retrieval-progress): Ditto.