Make soft/optional dependency for Templating component

[Koc]

Starting from Symfony 2.7 we can use twig directly without templating component. It could also improve performance a lot. But SonataBlockBundle has hard dependencies for this component and prevents disabling templating subsystem.

[soullivaneuh]

Do you have some docs about it?

Also feel free to propose a PR.

[Koc]

http://symfony.com/blog/new-in-symfony-2-7-twig-as-a-first-class-citizen

symfony/symfony#15028

[covex-nn]

@soullivaneuh this issue is not outdated, even after 2 years.

Well, for the templating part, the admin bundle should rather migrate to using the native Twig notation for templates, and using the Twig service directly. We precisely want to discourage the usage of the Templating wrapper in Flex projects.

(c) stof symfony/flex#247 (comment)

But to do this, second argument of AbstractBlockService::__construct must be changed from EngineInterface $templating = null to \Twig\Environment $twig = null. This is a lot of changes in all sonata-project bundles

• See https://github.com/sonata-project/SonataBlockBundle/blob/master/src/Block/Service/AbstractBlockService.php

[Koc]

ref #456