This significantly reduces the time necessary to render the ticket queue
page with the ORM.

And manage it with updates to tickets. This will ease the sorting and
display of tickets based on the time of last update in the ticket queues

This will contain the effective due date of the ticket — either the due date
or the estimated overdue time of the ticket based on the SLA settings. It
will be maintained with ticket updates.

orm: Add greater support for expressions in order_by

Also re-implement the "exclude answered tickets" and "exclude assigned
tickets" from open queue options.

Define a static ::getQuery() method and define 'view'=>true in the model
meta data and the SQL code retrieved from getQuery will be used inline when
joining the model rather than using a table.

QuerySet::extra() — allow for extra tables and where clauses initially, long
term, support extra fields in the SELECT and ORDER_BY clauses.

QuerySet::distinct() — allow for specifying distinct columns in the query

If a common model is used in more than one select_related model (user and
user__email), avoid fetching the columns for the user model more than once.

This adds support for things like

    SqlInterval::MINUTE(3)
    SqlExpression::minus(SqlFunction::NOW(), SqlInterval::DAY(1))

When using select_related with nullable relationships, ensure that when
constructing models, that a NULL object is retrieved when handling a null
relationship.

This allows stashing a forms current state and restoring it later

In-line forms are forms that are rendered as one field. The data of the
inline form is also saved in the data for one field. Currently, the data is
rendered to JSON and stashed in the database.

The data in the field is also accessible via the variable replacement
system, so something line %{ticket.field.subfield} can be handled by the
inline form field.