Merge branch '3.4' into 4.1

* 3.4:
  bump required Twig version

Author: fabpot

composer.json

@@ -17,7 +17,7 @@
     ],
     "require": {
         "php": "^7.1.3",
-        "twig/twig": "^1.36.1|^2.6.1"
+        "twig/twig": "^1.37.1|^2.6.2"
     },
     "require-dev": {
         "symfony/asset": "~3.4|~4.0",