[PATCH v3 0/6] send-email: cleaner tests and quote email

The purpose of this series of patches is to implement a new "quote-email" feature integrated in the current `--in-reply-to` option.

 * The first 2 patches make the tests less dependent to
   `git send-email`'s exact output.

 * Third patch makes `git send-email` a bit less verbose.

 * Fourth patch introduces our email parser subroutine.

 * Fifth patch makes the `--in-reply-to` open a email file (if it
   exists) and populates From:, To:, Cc:, In-reply-to and
   References: fields.

 * Sixth patch quotes the message body in the cover letter if
   `--compose` is set. Else, imply `--annotate` and insert quoted
   message body below triple-dash in the first patch.

General changes since v2:
 - Modify tests to be less dependent on `git send-email`'s exact
   output.
 - New email parser subroutine.
 - `--quote-email` option is now merged with `--in-reply-to`.
 - Add `--cite` option to quote the message body.
 - `git send-email` is less verbose.

 Documentation/git-send-email.txt |  17 +++++--
 git-send-email.perl              | 178 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++------
 t/t9001-send-email.sh            | 238 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----------------------
 3 files changed, 356 insertions(+), 77 deletions(-)