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>

Unassign tickets on transfer when the target department has assignment
restriction and the assigned staff is not a member.

Disable claim (quick self-assignment) when above restriction is in effect.

i18n: Ensure UTF-8 is used as the request encoding

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

ui: Dialog and overlay appear over tip boxes

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

Agent internal activity alert

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

email: (Correctly) parse priority to priority_urgency

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

lock: Disable navigation warning if not using the lock feature

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

thread: Defer loading email header information

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

email: Use \n as the default line ending

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

email: Some bounce notices actually have rich content

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

Here's an example email structure:
```
multipart/mixed
 - multipart/report; delivery-status
   - multipart/alternative
     - text/plain
     - text/html
   - message/delivery-status
   - message/rfc822
```

The previous code would only find the body if the email main headers had:
Content-Type: multipart/report; report-type="delivery-status". In such a
case it would scan for a plain/text body.

This patch will scan for the usual body if the scan for the body as usual if
the report scan did not find anything.

Also, output errors to stderr when running API from the command line

It seems that most systems handle the newline character alone without a
problem; however, some systems cannot handle the standard CRLF line ending
at all.

The %ticket_email_info table needs an index on thread_id. This is done in
the `develop-next` branch; however, this patch helps alleviate performance
issues on the main branch until the `develop-next` branch is collapsed for
main line development.

search: Fix search for unassigned tickets

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

forms: Fix unset of all checkboxes on a form

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