If osTicket was improperly or incompletely upgraded, then some tables may
exist which should otherwise not exist. This patch assists the upgrade
process by dropping the tables which should not exist prior to adding or
renaming tables.

This feature addresses a major issue with the initial implementation of the
custom data system. The original system confused the usage of
database-backed field (dynamic-fields) and their corresponding
implementation. This created the need to crate awkward caching pieces to
ensure that validation errors and data was maintained. Furthermore, the
system confused the linking between form instances (dynamic-entry) and the
form used to represent that entry.

This patch addresses the confusion in two ways:

Dynamic form entries do not link directly to the dynamic form. Instead, the
::getForm() method returns something from the forms API directly.
Furthermore, the ::getFields() method does not return dynamic field
instances (database backed / designed fields). Instead, the actual
implementation of the fields from the forms API is retrieved. This allows
the fields to *always* be cached, which helps preserve data and validation
state.

Secondly, the dynamic form uses the same system, so that requests to turn a
dynamic form into a form (via ::getForm) will also result in the same
behavior, again, where the fields are represented as forms API fields rather
than the dynamic fields.

So going forward, the dynamic fields are *only* used to create corresponding
forms API field implementations. The are associated with the dynamic
counterparts as sparingly as possible.

This patch includes a slight database migration, and adjusts the
functionality of a few core components.

  * Move collaborators from the ticket to the thread.
    This concept allows collaborators on any object which has a thread,
    including tasks.

  * Add flags to the thread entry
    This will allow flagging thread entries for different purposes.
    Initially this can be used to flag the original message of a thread in
    case a ticket / thread is created without an initial message.

  * Lock becomes more of a utility
    The lock is now disconnected from the ticket and is a separate utility.
    Separately, the ticket and task objects can have a reference to a lock
    object. Furthermore, when submitting some activities to tickets, the
    lock is verified to be owned by the respective agent, and the lock code
    must match a current lock code. The code is rotated on each acquire()
    call to guard against double submissions.

  * Collaborator is an ORM model
    The TicketUser class is broken up now so that the collaborator instance
    can exist apart from a ticket. Email message ids are now generated for
    collaborators without respect for a ticket so that collaborators can be
    properly supported on any thread.

This patch converts the central file and threading classes over to use the
ORM.

Make the upgrader play nice when loading latest yaml files.

This patch rebases filters into a row-based layout and redesigns the filter
apply method to be more extensible. It also redesigns the UI to be more
dynamic and to allow for actions to be added without database modification
and actions can also have complex configurations.

Help topics can now specify one or more additional forms to be included on
the help topic and can also specify the sort order of those forms.
Furthermore, individual fields can be disabled per help topic, so that
unnecessary fields can be omitted when necessary, per help topic.

The disabled flag is recorded along side the field data so that the field
will not be accidentally added to the form later automatically. There is no
interface in this commit to enable a field which was disabled by the help
topic when ticket was created.

Key permissions definition array
Move canned and faq permissions to their respective classes.

Handle missing `intl` module
Handle crash translating the staff login banner, when the %translation table
    does not yet exist
Handle `allow_client_updates` never having been configured
Handle staff login without @lang and @extra attributes in database

Support duplicate names in different hierarchy
Save path on add/update
Show full department name on transfer

This will look through the database and find images which appear to be
inlined in thread entries, but are not recorded as inline. It will update
the %ticket_attachment table to reflect the inline disposition of the
images.

Introduce the concept of tasks. Tasks are to do list that can be attached to
any object e.g Ticket.

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.

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.

Adds migration patch for role-based access

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