This patch adds an 'email' format to ThreadBody::display() which allows
formatting the html/text bodies specifically for email. Previously, there
was ambiguity between the html view (which included inline image support and
clickable links) and the email view, which requires neither.

Change v1.8.2 to v1.9.0
Drop help tips for list properties

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

The user should not have to step over it

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