Implemented disconnected operations (Not tested enough).

Implemented disconnected operations (Not tested enough).

* wl.el (wl-plugged-dop-queue-info): Fixed for new queue structure.

* wl-summary.el (wl-summary-mark-as-important): Set message number
using wl-summary-message-number.

* elmo.el (elmo-message-encache): Define as generic function.
(elmo-message-fetch-field): New generic function.
(elmo-message-fetch-with-cache-process): Cause an error when
fetch strategy is 'entire but only 'section cache is available.
(toplevel): Fixed nmz folder definition.

* elmo-vars.el (elmo-msgdb-lock-list-filename): Removed.
(elmo-msgdb-resume-list-filename): Ditto.
(elmo-queue-filename): Ditto.
(elmo-enable-disconnected-operation): Changed default value to t.

* elmo-util.el (elmo-cache-path-section-p): New function.
(elmo-file-cache-get): Use it.
(elmo-dop-queue-filename): Moved from elmo-dop.el.
(elmo-dop-queue-load): Moved from elmo-msgdb.el.
(elmo-dop-queue-save): Ditto.

* elmo-net.el (elmo-folder-status-unplugged): Call
elmo-folder-status-dop.
(elmo-folder-list-messages-unplugged): Implemented.
(elmo-folder-delete-messages-unplugged): Define.
(elmo-folder-msgdb-create): Define.
(elmo-folder-msgdb-create-unplugged): Define.
(elmo-folder-mark-as-read-unplugged): Ditto.
(elmo-folder-unmark-read-unplugged): Ditto.
(elmo-folder-mark-as-important-unplugged): Ditto.
(elmo-folder-unmark-important-unplugged): Ditto.
(elmo-message-encache): Ditto.

* elmo-msgdb.el (elmo-dop-queue-load): Moved to elmo-util.el.
(elmo-dop-queue-save): Ditto.

* elmo-imap4.el (elmo-folder-msgdb-create-plugged): Renamed from
`elmo-folder-msgdb-create'.
(elmo-folder-append-buffer): Implemented unplugged operation.
(elmo-folder-append-messages): Call parent method in unplugged status.
(elmo-message-fetch-unplugged): Removed definition.
(elmo-message-fetch-field): Implemented.

* elmo-dop.el (toplevel): Require 'elmo-localdir.
(elmo-dop-folder): Removed variable definition.
(elmo-dop-queue-append): Changed argument `fname' to `folder'.
(elmo-dop-queue-flush): Implemented.
(elmo-dop-queue-merge): Removed definition (TODO).
(elmo-dop-spool-folder): New function.
(elmo-dop-spool-folder-append-buffer): Ditto.
(elmo-dop-spool-folder-list-messages): Ditto.
(elmo-dop-list-deleting-messages): Ditto.
(elmo-folder-append-buffer-dop): Ditto.
(elmo-folder-delete-messages-dop): Ditto.
(elmo-message-encache-dop): New inline function.
(elmo-create-folder-dop): Ditto.
(elmo-folder-mark-as-read-dop): Ditto.
(elmo-folder-unmark-read-dop): Ditto.
(elmo-folder-mark-as-important-dop): Ditto.
(elmo-folder-unmark-important-dop): Ditto.
(elmo-folder-status-dop): Fixed.
(elmo-folder-append-buffer-dop-delayed): New function.
(elmo-folder-delete-messages-dop-delayed): Ditto.
(elmo-dop-msgdb): Ditto.