Update Twig from 1.35.0 to 1.42.4 (PHP 5.5 is now required!)

This fixes some errors on PHP 7.4 and contains even more fixes
Also bumped PHP version to 5.5 as Twig requires it.

system/libs/Twig/Extension/AbstractExtension.php

@@ -0,0 +1,72 @@
+<?php
+
+/*
+ * This file is part of Twig.
+ *
+ * (c) Fabien Potencier
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Twig\Extension;
+
+use Twig\Environment;
+
+abstract class AbstractExtension implements ExtensionInterface
+{
+    /**
+     * @deprecated since 1.23 (to be removed in 2.0), implement \Twig_Extension_InitRuntimeInterface instead
+     */
+    public function initRuntime(Environment $environment)
+    {
+    }
+
+    public function getTokenParsers()
+    {
+        return [];
+    }
+
+    public function getNodeVisitors()
+    {
+        return [];
+    }
+
+    public function getFilters()
+    {
+        return [];
+    }
+
+    public function getTests()
+    {
+        return [];
+    }
+
+    public function getFunctions()
+    {
+        return [];
+    }
+
+    public function getOperators()
+    {
+        return [];
+    }
+
+    /**
+     * @deprecated since 1.23 (to be removed in 2.0), implement \Twig_Extension_GlobalsInterface instead
+     */
+    public function getGlobals()
+    {
+        return [];
+    }
+
+    /**
+     * @deprecated since 1.26 (to be removed in 2.0), not used anymore internally
+     */
+    public function getName()
+    {
+        return \get_class($this);
+    }
+}
+
+class_alias('Twig\Extension\AbstractExtension', 'Twig_Extension');