Merge branch 'topic/smtp'

Merge branch 'topic/smtp'

* topic/smtp:
  sendout.c:_message_id(): shorten it; temporary URL ident hack
  sendout.c: "localize" SEND_LINESIZE
  Add SMTP support for *v15-compat* and *smtp-hostname*
  url_parse(): add CPROTO_SMTP <-> *smtp-hostname* support
  nodename(): query sys_hostname() only once
  Add count_nonlocal()
  nail.h: add struct sendbundle
  nail.h, nail.1: add *smtp-hostname*
  Add GSS-API for SMTP (request+testing Tarqi Kazan)
  Add SUBMISSION protocol (RFC 6409)
  SMTP: use new user credential layer, drop smtp_auth_var()..
  smime_sign(): string not struct header argument
  outof(): drop unused struct header argument