Commit c4579277 introduced an extra administrative security feature to
restrict files access to signed in users only, even  if a user has a valid
& signed download URL. The feature, however, did not take into account
public images & files associated with FAQs and pages such as
landing/thank-you pages.

This commit addresses the shortcoming by adding a reference ID (attachment ID)
to the download/access URL, that can be used to deduce the model/object type
that the file request is associated with. The technique will allow us in the
future to enforce ACL at the file level depending on privacy settings and
the security clearance of the user (agent).

This addresses issue #3860 where if you add a translation to the Login
Page and view the page in the translated language, the translation does
not show. This adds the correct method to get the translated page.

Update two phrases with from "Internal error - Try again!" to "Internal error occurred - Try again!" since it's the most common phrase

Updated several files to split up phrases like "Your lock has expired. Please try again!" into "Your lock has expiredx" and "Please try again!"

This pass also makes a stride at adding correct punctuation and making error
phrases consistent.

This is my attempt at removing similar texts from the translator work load.
It also makes an attempt at dropping some misspelled words and works toward
standardizing some phrases.

Previously, the create method was used to create a new instance of an orm
model (which would later result in an INSERT when persisted); however, some
classes require or utilize varying parameters to their create() method,
which PHP7 considers an error. Methods in subclasses must be defined with a
calling signature compatible with the parent class.

This patch shifts the concept of model creation to the constructor. Now, the
constructor of ORM models is required to be compatible with that of
ModelBase class. Now that most models do not define a constructor, this is
much easier to control, and much more logical.

Also, remove an issue where assignments on a relationship field to an
instance of a super class of the foreign model would raise an error. This
was previously addressed by re-classing the instance in the
ModelInstanceManager::getOrBuild(); however that design would create
multiple instances of the same object in memory, which defeats one of the
primary design concepts of the ORM. This patch addresses the issue by
allowing super-classes of the declared foreign model in relationship
assignments.

* Fix crash saving a page (regression)
* Fix red banner deleting a department
* Fix crash deleting a knowledgebase article

* Fix attachments not sticking on new dynamic form entry
* Fix attachments not sticking on thread post validation error
* Fix missing inline images in FAQ article viewing
* Fix missing inline images in FAQ article printing
* Fix crash rendering sidebar in staff faq view with attachments
* Rewrite GenericAttachments to be an ORM object
* Port CannedResponse to ORM
* Fix attachments not being displayed when editing a FAQ article
* Fix squirly empty blue box on faq articles with no attachments

Allow the staff banner to be set to empty (which is the default).

Also display the update errors back on the dialog for failed updated.

Don't crash when login-banner page doesn't exist yet.

  * Fix translation of pages
  * Localize client thank-you page on new ticket
  * Fix adding new category
  * Fix crash on staff login when upgrading from < 1.9
  * Don't show self locks on ticket queue pages

This script adds a single download script, 'file.php', which provides access
to files of all types to all users. It uses a HMAC signature system with an
expires time, which allows signed URLs to be sent to external users.

This also fixes an issue with the Http::cacheable() method, where the
last-modified and Etag headers were not properly compared, which resulted in
permanent cache misses by the client.

That way, the format can be standardized and the code can be reused among
other translatable objects such as the knowledge base.

Store a complex text with title and body combined with ASCII 0x04 byte
(field seprator).

Also add some logic to the POT builder to warn about incorrect arguments to
the __() function and friends as well as warn about _() usage.

Also add images on pages to the drop-down list for image choosing, and fix
display of images on the client portal.

Process inline attachments in thread entry and support inline images in
piped emails

Support inline images across the system, with draft support

Migrate to a single attachment table
    That way we don't need a new table for everything we need to attach an
    inline image to (like a signature, for instance)

Add richtext support for internal notes

Implement images on site pages

* Image paste in Redactor
* Make non-local images optional
* Placeholder for non-local images
* Fix local image download hover
* Don't re-attach inline images

 - Supported pages: landing, offline, thank-you and other