mail_daemon: ESMTP auth fix (250 AUTH reply)

See RFC 5231 (https://tools.ietf.org/html/rfc5321): "Following the normal
syntax for multiline replies, these keywords follow the code (250) and a
hyphen for all but the last line..."

Change-Id: I1ee533a332d1e18ffddd4ad1520d14f4013b739e
Reviewed-on: https://review.haiku-os.org/670
Reviewed-by: waddlesplash <waddlesplash@gmail.com>

SMTP: Use B{Secure}Socket for communication.

SMTP: Remove STARTTLS support.

* It's vulnerable to man-in-the-middle attacks (which can't really be fixed)
* It's rather nasty to implement (and prevents us from using BSecureSocket)
* Nearly all servers I know of which support STARTTLS also support plain
TLS also.

SMTP: Fix coding style violations.

SMTP.cpp: fix gcc6 build

* Add curly braces to fix '-Werror=misleading-indentation' warnings.

Signed-off-by: Augustin Cavalier <waddlesplash@gmail.com>

SMTP works again.

* The message to send the mails never made it to the add-on looper.
* Mail protocol threads now have names.
* Added a "public" BOutboundMailProtocol::SendMessages() call that sends
itself a message (even the correct one this time).

SMTP: properly use const, and extern "C".

* This fixes having it picked up in the mail_daemon. That shouldn't have
worked in the last three years...

Fixed C++11 warnings.

invalid suffix on literal; C++11 requires a space between literal and string macro
[-Werror=literal-suffix]

Mail Kit: Changed how filter changes work.

* BMailFilter::HeaderFetched() now only alters the entry_ref, and returns
B_MOVE_MAIL_ACTION to move a mail.
* Instead of potentially moving the file around several times, the
BMailProtocol now takes care of carrying out the filter action just once,
including trying to make the file name unique.
* This also allows the IMAP add-on to know the final location of the mail,
and thus downloading a message actually works.
* However, with my test inbox, it currently hangs, and a current Debugger does
not work on my older system -- I guess I need to update.
* Replaced the duplicated space mechanism within the "HaikuMailFormatFilter"
that is substantially faster, and handles all whitespace, not just spaces.
It will also replace tabs with spaces.

Renamed smtp.{cpp|h} to SMTP.{cpp|h}.

Fixed C++11 warnings.

invalid suffix on literal; C++11 requires a space between literal and string macro
[-Werror=literal-suffix]

Mail Kit: Changed how filter changes work.

* BMailFilter::HeaderFetched() now only alters the entry_ref, and returns
B_MOVE_MAIL_ACTION to move a mail.
* Instead of potentially moving the file around several times, the
BMailProtocol now takes care of carrying out the filter action just once,
including trying to make the file name unique.
* This also allows the IMAP add-on to know the final location of the mail,
and thus downloading a message actually works.
* However, with my test inbox, it currently hangs, and a current Debugger does
not work on my older system -- I guess I need to update.
* Replaced the duplicated space mechanism within the "HaikuMailFormatFilter"
that is substantially faster, and handles all whitespace, not just spaces.
It will also replace tabs with spaces.

Renamed smtp.{cpp|h} to SMTP.{cpp|h}.