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.

Introduce the initial concept of adding tasks to a ticket.

The size of the dialog can be auto-adjusted based on the options

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

This will disable the ability for a user to close a ticket when they
have not filled out all of the required fields. Explains the problem to
the user trying to close and directs them to the edit page. Added some
functions to the $ticket class to make it easy to determine the missing
required fields.

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

Move the attachments to the sidebar, add the concept of language-specific
attachments. Add a sidebar to the front page. De-emphasize the "open new
ticket" button. Add a knowledge base search feature to front page and also
add the concept of "featured" articles and categories on the front page.

Also complete the translation client-side

This reworks the tabs CSS and javascript coding to be more flexible and to
support vertical tabs. (Bootstrap calls this stacked.) The javascript also
allows the URL to include the hash-tag of the last-clicked tab so that the
tab can be automatically shown when the page is reloaded.

This allows fields to specify a visibility constraint that will be evaluated
in real time in the browser to automatically show and hide fields that
should be hidden based on values of other fields in the same form.

Validation is not performed on fields server-side if they are considered
invisible when submitted.

Crowdin recreates YAML files with indent specifications which Spyc does not
currently handle:

body: |2
  body contents written
  here with 2 leading spaces

This is part of the Yaml spec after 1.0

backportme

Ticket numbers are now configurable as a system-default and by help topic.
Previously, an administrator could select between six-digit random and
sequential numbers. Now, the sequence is selectable so multiple sequences
as needed, and a format can be specified to define how the ticket numbers
look. Formats can also be defined for each help topic.

Remove retired navigation background image