Update Twig to version 2

[EvanLovely]

Since Drupal 8.4 will use Twig 2 (anybody have source link, I couldn't find one with a quick search), let's get on this. Originally posted here: pattern-lab#41 by @renestalder /cc @sghoweri

[sghoweri]

That Drupal 8.4 target release is mentioned here but according to the issue that links to it looks like it might not make it till Drupal 8.5: https://www.drupal.org/node/2572605

Either way I still think we should get the ball rolling on this just to be safe, especially if this take a bit of time to get to

[Farnoosh63]

Is there an update on this?

[renestalder]

@Farnoosh63 I think the PHP version of Patternlab is no longer developed. Your best chance (that's also what I'm going to do) is, to migrate to the node version of patternlab and use the recently released Twig engine edition there.

I'm not sure what Twig specification the node implementation of Twig uses, but I'm convident it will not be Twig 1.

[remydenton]

Switching to the node version wasn't an option for us, so I forked this repo and made some quick and dirty updates to support twig 2. I won't create a PR since it's quick and dirty, but here it is for reference in case others find themselves in the same situation: https://github.com/remydenton/patternengine-php-twig/tree/twig-upgrade