Log Message:
Update to 20181108. Changes:

- Add STARTTLS support to fixsmtpio(8), which needs to terminate TLS in
  order to continue observing requests and responses and do its job.
- Restore missing trailing " ESMTP" in greeting.
- Fix all warnings in acceptutils code.
- Document FIXSMTPIODEBUG, UCSPITLS, and DISABLETLS.