Handle cases where status change fails

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

forms: Several minor fixes for properties and search integration

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

Furthermore, revamp the __cdata system to better support multiple selection
fields. Drop the `.._id` fields and use a coalesce of the ID value of the
entry value or the entry value itself. For JSON backed fields, strip some
JSON characters to result in a comma-separated list.

The search engine now uses MySQL FIND_IN_SET to analyze a search selection
in advanced searches. Also, interaction with the MySQL full text search
backend is fully supported.

Set the correct error message and maintain user selection & input

Not just the SelectionField. This will make room for the InlineFormField

forms: Add all forms to the filter subsystem

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

forms: Better feedback for client side upload fails

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

Statuses revisited (again)

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

Make the error message clear

Conflicts:
	include/class.export.php
	include/client/login.inc.php
	include/staff/ticket-view.inc.php

Sanity check for callable check

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

forms: Drag and drop uploads

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

Attachment settings are now exclusively handled by the settings on the
ThreadEntry field on the ticket details form. Enabling attachments as well
as tuning attachment validation settings are all handled from the one place
now.

Only one file is supported at a time now; but at least the files are saved
and displayed in the event of validation errors.