Merge remote-tracking branch 'kevin/issue/ticket-preview-custom-fields' into features_prs/develop-next

Merge remote-tracking branch 'kevin/issue/disable-canned-responses-on-new-ticket' into features_prs/develop-next

Merge remote-tracking branch 'kevin/issue/local-field-names-in-errors' into features_prs/develop-next

Merge remote-tracking branch 'kevin/issue/private-faq-search-sidebar' into features_prs/develop-next

This addresses issue 4112 where osTicket does not have a default favicon.
This adds favicon images and references to them in the Agent and
Client headers so they appear correctly.

Exclude user lookup done on ticket create from Recent Searches

This addresses an issue where some Vimeo videos are not being sent in
Agent’s responses. This adds `player.vimeo` to the sanitize method’s
iframe section so that the iframe tag is not stripped.

* Export all exportable fields by default - for all queues + adhoc searches
* Export Due Date as well as SLA Due Date

Add ability to add sticky export fields for queues.

* Due date vs. SLA due date
* Misc. datetime fixes

Add ability to edit individual fields without the need to mass-edit all
fields.

Conflicts:
	include/class.thread.php
	include/class.ticket.php

Add support auto email-based auto-referral. This will happen if an email is
sent to multiple departments. For example an email with TO: support &  CC:
billing will result in the ticket getting routed to "support" department and
"billing" getting a referral of the same ticket. This allows both departments
to have visibility of the ticket - which is not possible at the moment.

Move referral checking to thread class

This addresses an issue where the `randNumber()` function would crash on
32-Bit systems if the ticket format was set to a really high amount of
digits (eg. ###################). This is because the `max()` value that
was being passed to `mt_rand()` exceeded the `mt_getrandmax()` limit which
caused an error. This updates the function to generate a random number for
each digit to avoid the `mt_getrandmax()` limit.

This addresses an issue where someone can “takeover” an account with only
a User’s email and a User’s previous ticket number. Once they get access
to a User’s ticket they can go to the Ticket Owner’s profile and change
the email to whatever they’d like. This adds a check on the profile to see
if the User is a Guest User. If they are a Guest then it kicks them back
to the ticket view. If they are the actual User it will let them view the
profile.

cron: Delete Expired Sessions

This addresses an issue where the Help Text for Section Break fields does
not display custom Redactor styling correctly. Instead of displaying the
properly formatted Redactor content with it's styling it displays the
entire html for the Redactor content. This was due to the format method
used for the Section Break Field's Help Text. This updates the method from
`Format::htmlchars()` to `Format::display()` which displays the properly
formatted content. The content is also sanitized by `Format::sanitize()`
before saving to the database to avoid any chance of XSS.

Move referral checking to thread class