Detach conversation thread from ticket to make it more generic. Any object
can now have its own thread complete with entry type and attachments.

Use generic attachment table for all attachments system-wide.
Drop thread entry attachment table

Detach conversation thread from ticket to make it more generic. Any object
can now have its own thread complete with entry type and attachments.

The commit also renames some fields in department table.

Adds migration patch for role-based access

The commit also renames some fields in department table.

Conflicts:

	include/i18n/en_US/form.yaml
	include/staff/templates/dynamic-field-config.tmpl.php
	include/staff/ticket-view.inc.php
	include/staff/tickets.inc.php
	scp/js/scp.js

oops: Fix crash upgrading to c7c82835

oops: Fix crash rendering ticket view

oops: Fix crash posting response to ticket

oops: Fix refresh url after ticket reply post

orm: Locate annotations after the root model's fields

orm: Add PK field check for DISTINCT aggregate expressions

When using the DISTINCT option for aggregate expressions, ensure that when a
relationship is used in the aggregate, that a single field of the remote
model's primary key is used — rather than the foreign key, since it would
never have more than one unique value.

search: Re-implement basic ticket search

oops: Couple trivial changes

oops: Fix date formatting for PDF output

oops: Fix staff profile view and update

oops: Fix canned response listing

orm: Fix crash compiling WHERE IN (nested select)

nav: Move settings/email to email/settings

i18n: Make field visibility config translatable

oops: Fix crash adding field to custom form

forms: Fix `required` flag transfer to FormField

oops: Fix bad merge on new ticket by staff

forms: Show uneditable fields on new ticket by staff

oops: Fix bad merge on client ticket view

Adds migration patch for role-based access

Introduce the concept of role-based access for agents.

The commit also renames some fields in department table.