Merge branch 'ag/send-email-imap-sent'

"git send-email" learned to drive "git imap-send" to store already
sent e-mails in an IMAP folder.

* ag/send-email-imap-sent:
  send-email: enable copying emails to an IMAP folder without actually sending them
  send-email: add ability to send a copy of sent emails to an IMAP folder

diff --cc Documentation/git-send-email.adoc
Simple merge

diff --cc imap-send.c
Simple merge