* elmo2.el (elmo-quit): Don't use `elmo-nntp-flush-connection'.

* elmo2.el (elmo-quit): Don't use `elmo-nntp-flush-connection'.

* elmo-nntp.el (elmo-nntp-session): Define.
(elmo-nntp-setting): Abolished.
All other related portions are changed.
(elmo-nntp-get-server-command): Changed argument.
(elmo-nntp-set-server-command): Ditto.
(elmo-nntp-xover-p): Ditto.
(elmo-nntp-set-xover): Ditto.
(elmo-nntp-listgroup-p): Ditto.
(elmo-nntp-set-listgroup): Ditto.
(elmo-nntp-list-active-p): Ditto.
(elmo-nntp-set-list-active): Ditto.
(elmo-nntp-xhdr-p): Ditto.
(elmo-nntp-set-xhdr): Ditto.
(elmo-nntp-flush-connection): Abolished.
(elmo-nntp-get-connection): Abolished.
(elmo-nntp-get-session): New function.
(elmo-network-initialize-session): Defined.
(elmo-network-authenticate-session): Ditto.
(elmo-nntp-send-mode-reader): Changed argument.
(elmo-nntp-send-command): Changed argument.
All other related portions are changed.
(elmo-nntp-read-response): Ditto.
(elmo-nntp-read-raw-response): Ditto.
(elmo-nntp-read-contents): Ditto.
(elmo-nntp-read-body): Ditto.
(elmo-nntp-goto-folder): Abolished.
(elmo-nntp-select-group): New function.
All other related portions are changed.
(This function substitutes `elmo-nntp-goto-folder')
(elmo-nntp-msgdb-create-by-header): Rewrite.
(elmo-nntp-get-overview): Eliminated.
(elmo-nntp-get-message): Ditto.
(elmo-nntp-open-connection) Abolished.
(elmo-nntp-read-msg): Rewrite.
(elmo-nntp-post): Ditto.
(elmo-nntp-send-data): Abolished.
(elmo-nntp-send-buffer): New function.
(elmo-nntp-send-data-line): Define as inline function.
(elmo-nntp-get-folders-info-prepare): Use session as key.
(elmo-nntp-groups-read-response): Changed argument.
(elmo-nntp-retrieve-headers): Ditto.
(elmo-nntp-msgdb-create-message): Ditto.

* elmo-msgdb.el (elmo-msgdb-search-internal-primitive): Fixed problem
when searching by 'since' or 'before'.