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>

Fixes #1854

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

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.

When the user is not identified by the web interface, such as processing
email to tickets, attempt to locate and include the user filter information
when matching the filter to the new ticket data.

If an update to an object such as a ticket results in a corresponding update
to the CDATA table, and one or more of the fields have been deleted from the
ticket details form, then, avoid updating the CDATA table for those fields.

This fixes an issue where the CDATA table is dropped and recreated when
fields are added and removed from the form. The table will only contain
fields which are currently on the form when the table is created. Therefore,
deleted fields will never be on the CDATA table and will result in an SQL
error.

thread: Avoid crash with multiple Message-ID headers

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

Unassign on transfer

Reviewed-By: Jared Hancock <jared@osticket.com>

email: Add warning for archive folder for POP

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

This patch adds an error to the page if unable to configure the archive
folder and POP was selected as the mailbox protocol. Generally, POP servers
do not support anything but the INBOX

Mass actions for user directory

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