Allow stylesheet for printing

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

forms: Don't save on validation errors

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

Also, write js and css links to be forcibly reloaded by the browser after
deployment

As suggested by: https://github.com/osTicket/osTicket-1.8/issues/755

Alert on Internal Note

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

Send an alert to assigned staff/team on an internal note even when a ticket is
closed.

bug: "No Alerts" on assignment for teams

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

oops: Fix a few small issues

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

Enhancements

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

Add ability to disable canned responses
Fix team drop down selection
Remove priority escalation setting in SLA page (implementation is on todo
        list)

captcha field without autocomplete

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

oops: Add "size" to allowed API properties for attachments

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

Fix images in new ticket notice to end user

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

Show close date on closed tickets queue

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

Make mail parsing more memory efficient

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

Remove usage of preg_match_all for large strings

bounce: Handle rfc/1892 style bounce notices

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

alerts: Send new note alert to assigned team members

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

Sometimes an MTA may just send back the headers of the original message
rather than the entire original message. Such an email will have a
`text/rfc822-headers` part which will be the complete headers of the
original message.

Without this patch, osTicket will create a new ticket for the bounce message
rather than attaching the new internal note to the existing ticket.

References:
https://tools.ietf.org/html/rfc1892

Consider closed date to determine ticket's last activity date. The net effect is closed tickets queue will be sorted by closed date.

Departments without email will use the system default email as the default
outgoing email.

The setting is useful in making sure the staff members with access to the
department can get alerts and available as possible assignees.

Accept desired $format as part of class instantiation. System default is
used when none or an invalid format is provided

Add department setting to limit ticket assignment within department to
department members only. This is necessary for departments with strict
policy on who can access tickets.

The setting doesn't limit team assignment or auto-assignment via help topics
and ticket filters.

This patch uses a 'StringView' to create a string which is a window of
another string. The __toString() method is employed to fetch a lazy copy of
the window which can be usually immediately discarded. This is optimal for
one-time-use string copies like what is used in the mail parsing.