This is useful when testing.

It was deprecated in Twig 1.x and removed in 2.0.

This introduces the following:

- The use of Request objects to handle request data to controllers.
- The use of Response objects to model responses that should be sent to the browser.
- The use of "controllers" that are responsible for translating a request into a response.
- The possibility to define your own URLs on each module by specifying them, together with their controllers, in a "routes.yaml" file in the root of a module.
- The new UI is completely separated from the old, so "usenewui" must be set to "true" in the configuration.
- Twigified templates are not used unless we're using the new UI, or the twig template is part of a theme.

There's some redundancy now since the code must support the old
and new template. The links variety is not very beautiful, but the
old one wasn't either..

This seemed the logical place to do it, because it's essentially
a presentation thing (so in Template, not Locale). There's likely
something to be said for sorting by key aswell as sorting by
translated language name. Picked key for now, seems most predictable.

setupTwigTemplatepaths() cannot return false

This seemed the logical place to do it, because it's essentially
a presentation thing (so in Template, not Locale). There's likely
something to be said for sorting by key aswell as sorting by
translated language name. Picked key for now, seems most predictable.

Now we can load templates in twig with two syntaxes:

- The original twig syntax: "@module/path/to/template.twig"
- The SSP syntax: "module:path/to/template.php" or "module:path/to/template.tpl.php"

This allows us to load templates from modules inside a twig template itself (include, embed, etc), even when the main template is not in a module or in a different one.

This can be used by templates to load resources in different ways, either optimized for the developer or for a production environment.

This allows us to use this new filter to translate strings from a given array of translations, where every translation is indexed by its ISO 639 code. A new configuration option ('language' -> 'priorities') is available too to control the alternative languages that can be used instead of a given language, when the latter is not found. The filter returns null when no suitable translation is found, so that it can be combined with "default()" to set a default translation for a given string.