Update to Symfony 4

I`ve been told from my developers, that Grav still runs on Symfony 2, while Symfony 4 was already released. We want to use it for a huge Project and this was on of the major concerns. Is there any plans to update this any time soon?

As answered on the Github issues, Symfony 4 has much stricter PHP requirements than Grav does. This means that we would have to only support PHP 7.1.3+, while currently, Grav supports PHP 5.5.9+.

We do plan on increasing our PHP requirements in the near future but only to 5.6+ as that is still in security maintenance mode. We want to ensure we can continue to provide features and updates to existing Grav users who may not be in a position to move to PHP 7.1 at this point. Also, We are only using a minimal amount of functionality of Symfony, so the version is not so critical to us.

We do plan on increasing the requirements for Grav 2.0 significantly, and this will be our chance to get on more current versions of things (Symfony, Doctrine, Twig, etc)