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

This will simplify where PJAX needs to be disabled by simply including the
navigation as part of the PJAX response.

And extend the information to email templates

*This is a major redesign / rework of the osTicket base*

This patch drops the concept of static ticket metadata and allows for an
admin-configurable arbitrary data that is attachable to tickets

The system is architected such that the base osTicket install now comes with
a "default" form that has fields for subject, name, email, and phone number.
This form is editable to allow for the addition of arbitrary other fields;
however, the basic fields must remain in order to be associated with a
help-topic and attached to a ticket.

This concept can be expanded to allow for arbitrary data associated with
registered clients or ticket thread items.

Forms are comprised of sections. Sections have a title and instructions
properties and a list of fields. Fields have various implementations to
represent different data such as text, long answer, phone number, datetime,
yes/no, and selections, and are configurable to define the look and feel and
interpretation of the respective form field.

Dropdown lists are represented as "Dynamic Lists", which are
admin-configurable lists of items. Dropdowns can be optionally represented
as Bootstrap typeahead fields.

This also adds the start of a simple ORM which will hopefully be expanded in
the future to support multiple database platforms. Currently, only MySQL is
implemented.

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

Use minimized version of css.

Change header to match the new names

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

And correct several undefined function errors from several source files. So
while function names in PHP are considered case-insensitive, it still makes
sense to use consistent camel casing for both defining and calling methods.
The lint test searches the code base for method calls, and then searches the
code base again looking for a function definition matching the name of the
function invoked. It's not failsafe, because it doesn't detect the class
from which the method should belong, so it's likely to have false negatives.
Furthermore, it won't work well for PHP 5 where several classes are built
into PHP (and aren't searchable in the osTicket code base).

Remove the include/staff/api.inc.php as it no longer appears to be used (and
contains references to undefined methods).