upgraded to symfony 4 #74 (#81)

config/packages/twig_extensions.yaml

@@ -0,0 +1,12 @@
+services:
+    _defaults:
+        public: false
+        autowire: true
+        autoconfigure: true
+
+    #Twig\Extensions\ArrayExtension: ~
+    #Twig\Extensions\DateExtension: ~
+    Twig\Extensions\IntlExtension: ~
+    #Twig\Extensions\TextExtension: ~
+    Twig\Extensions\StringLoader:
+        class: Twig_Extension_StringLoader