* Paper sizes
  * More prompts on ticket filters

References:
(Crowdin login required)
http://i18n.osticket.com/translate/osticket-official/148/enus-de#4407
http://i18n.osticket.com/translate/osticket-official/148/enus-de#2379

The terms `%d open|closed tickets` need to be made plural so that the terms
`open` and `closed` can be properly translated.

References:
(Crowdin login required)
http://i18n.osticket.com/translate/osticket-official/148/enus-de#3735

The software defines at least three contexts for the phrase "Open"

  * The name of a ticket queue (Open tickets)
  * A status of a ticket (Open / Closed)
  * An action to be performed (Open a ticket)

References:
(Crowdin login required)
http://i18n.osticket.com/translate/osticket-official/148/enus-de#2915

Also, the final version of the system will not require the `gettext`
extension for PHP

Use a PHP source file for the translation hash table rather than a
serialized version of the array. This will allow a PHP object cache such as
APC to cache the file and remove the overhead of parsing and unserializing
on each request.

Fixes #145

This requires a hidden setting for the system language or the language
selection of the client (also currently hidden).