* elmo-util.el (elmo-number-set-member): New function.

* elmo-util.el (elmo-number-set-member): New function.
(elmo-number-set-append-list): Ditto.
(elmo-number-set-append): Ditto.

* elmo-msgdb.el (elmo-msgdb-killed-message-p):
Use `elmo-number-set-member'.
(elmo-living-messages): Ditto.
(elmo-msgdb-set-as-killed): Use `elmo-number-set-append'.
(elmo-msgdb-append-to-killed-list): Use `elmo-number-set-append-list'.

* elmo-imap4.el (elmo-imap4-folder-exists-p): Rewrite.
(elmo-imap4-add-to-cont-list): Abolished.
(elmo-imap4-make-number-set-list): Use `elmo-number-set-append'
instead of elmo-imap4-add-to-cont-list.

* elmo2.el (toplevel): Removed autoload setting for `elmo-imap4-get-connection'.