Use prepared process handling functions instead of own codes
* elmo/acap.el (acap-network-stream-open, acap-open)
(acap-close, acap-wait-for-response): Use process-live-p.
* elmo/elmo-imap4.el (elmo-imap4-read-response)
(elmo-network-initialize-session): Use process-live-p.
* elmo/elmo-net.el (elmo-network-get-session)
(elmo-open-network-stream): Use process-live-p.
(elmo-network-session-starttls-negotiate): Use process-type.
* elmo/elmo-nntp.el (elmo-network-initialize-session): Use
process-live-p.
* elmo/elmo-pop3.el (elmo-network-close-session)
(elmo-network-initialize-session): Use process-live-p.
* elmo/elsp-bsfilter.el (elmo-spam-list-spam-messages): Use
process-live-p.