* modb.el (elmo-msgdb-flag-available-p): New generic function.

* modb.el (elmo-msgdb-flag-available-p): New generic function.
(elmo-msgdb-message-number): Ditto.
(elmo-msgdb-message-field): Ditto.

* modb-standard.el (modb-standard-economize-entity-size): New user
option.
(modb-standard-loaded-message-id): New inline function.
(modb-standard-load-entity): Use it.
(modb-standard-save-entity-1): If `modb-standard-economize-entity-size',
throw message-id string away.
(elmo-msgdb-flag-available-p): Define.
(elmo-msgdb-message-number): Ditto.
(elmo-msgdb-message-field): Ditto.

* modb-legacy.el (modb-legacy-flag-list): Fix typo
(suppoted -> supported).
(modb-legacy-supported-flag-p): Ditto.
(elmo-msgdb-set-flag): Ditto.
(elmo-msgdb-unset-flag): Ditto.
(elmo-msgdb-flag-available-p): Define.

* modb-entity.el (elmo-message-entity-handler): If CAR element of entity
is `t', treat it as legacy entity.

* elmo.el (elmo-message-flag-available-p): New generic function.
(elmo-message-number): Ditto.
(elmo-message-field): Use `elmo-msgdb-message-field'.

* elmo-vars.el (elmo-preserved-flags): Added `forwarded'.

* elmo-pipe.el (elmo-message-flag-available-p): Define.
(elmo-message-number): Ditto.

* elmo-multi.el (elmo-message-number): Define.
(elmo-message-flag-available-p): Ditto.

* elmo-filter.el (elmo-message-flag-available-p): Define.
(elmo-message-number): Ditto.

* elmo-flag.el (elmo-flag-folder): Added slot `max-number'.
(elmo-folder-initialize): Load `max-number'.
(elmo-folder-commit): Save it.
(elmo-folder-list-global-flag-messages): Use `elmo-message-number'.
(elmo-global-flag-set-internal): Set up max-number slot.