Use twig and twig-bridge.

PHP 5.4 is actually needed because of the traits.
Add basic Twig template structure with block extends
Configure twig template dir
Register TwigServiceProvider with the app
Use the TwigTrait for the application.

This allows to call `$app->render()` directly instead of:

    $app[twig]->render();
Render the twig template in the controller