Fixes oversize image display to be resized in both the ticket thread and
the redactor editor in (at least)

  * Ticket-view boxes
  * Client new-ticket form
  * Staff new ticket
  * Page add/edit
  * FAQ add/edit
  * Canned response add/edit

Fixes osTicket/osTicket-1.8#247

Process inline attachments in thread entry and support inline images in
piped emails

Support inline images across the system, with draft support

Migrate to a single attachment table
    That way we don't need a new table for everything we need to attach an
    inline image to (like a signature, for instance)

Add richtext support for internal notes

Implement images on site pages

* Image paste in Redactor
* Make non-local images optional
* Placeholder for non-local images
* Fix local image download hover
* Don't re-attach inline images

Protect againts cross-site request forgery attacks by requiring a special
form-field or header to be sent with requests that modify ticket system
data.

This meant a slight change to the AJAX ticket locking mechanism. It was
defined to lock with a GET request; however, GET requests are defined as
safe methods and should not modify backend data (such as a lock
acquisition). Therefore, the the lock acquire AJAX method was changed to
require a POST method.

Also remove old, no-longer-used staff panel include files