New feature: You can have multiple template providers each one with it's own configuration 

Now you can specify a name for the service being registered, instead to be forced to use the default 'twig'

$app->register( new TwigServiceProvider('myTwig'), array( myTwigInstanceConfig );

You can found more info why it is useful at :
https://github.com/colegatron/SilexMultipleTwigServiceRepository