html: Ensure text internal note preserved

Reviewed-By: Peter Rotich <peter@osticket.com>

Preserve text formatting on the internal note posted to a new ticket by
staff if HTML thread is disabled.

tnef: Fix various TNEF processing issues

Reviewed-By: Peter Rotich <peter@osticket.com>

email: Properly detect bounce message with alternative content

Reviewed-By: Peter Rotich <peter@osticket.com>

fix translation for "Add new list"

Reviewed-By: Peter Rotich <peter@osticket.com>

Fix a few translatable phrase issues

Reviewed-By: Peter Rotich <peter@osticket.com>

mailer: Embed the Message-Id token in @class

Reviewed-By: Peter Rotich <peter@osticket.com>

Ensure consistent name formatting for agents and end users

Reviewed-By: Peter Rotich <peter@osticket.com>

email: Support agents emailing as collaborators

Reviewed-By: Peter Rotich <peter@osticket.com>

This correctly handles a bounce message with the following layout:

multipart/report; report-type=delivery-status
    multipart/alternative; differences=Content-Type
        text/plain; charset="us-ascii"
        text/html; charset="us-ascii"
    message/delivery-status
    message/rfc822

Fixes #1854

Several mail clients do not return the Message-ID header in a In-Reply-To or
References header as they should. The assumption by such mail clients is
that the email be threaded based on the Subject header. However, osTicket
does not require the ticket number to be placed in the Subject header and so
has trouble threading email from such systems. osTicket embeds a copy of the
Message-ID header (or compatible version) in the body of the message in
hopes part of the message will be returned.

Many mail clients (such as osTicket) strip and clean the HTML when
processing HTML email. Previously, the message-id token was embedded in a
@data-mid attribute, which was likely stripped before the HTML email would
be returned back to osTicket.

This patch suggests that the token be placed in a @class attribute, which
has a much better chance of returning to osTicket.

Fixes #1926

Also fix bug where bogus charset names like `iso` were confused with valid
charset names starting with that text, such as `iso-8859-2`.

add __() function for not translated words.

forms: Don't update CDATA when updating old fields

Reviewed-By: Peter Rotich <peter@osticket.com>

Fix several issues with user directory objects

Reviewed-By: Peter Rotich <peter@osticket.com>

mailer: Try harder to find References header

Reviewed-By: Peter Rotich <peter@osticket.com>

filters: Filter user information for email tickets

Reviewed-By: Peter Rotich <peter@osticket.com>

Ensure that the References header that is included with outbound email
definitely includes the References header from an email received into the
system, if at all possible.