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/Twig/Loader/Array.php

@@ -0,0 +1,11 @@
+<?php
+
+use Twig\Loader\ArrayLoader;
+
+class_exists('Twig\Loader\ArrayLoader');
+
+if (\false) {
+    class Twig_Loader_Array extends ArrayLoader
+    {
+    }
+}

system/libs/Twig/Twig/Loader/Chain.php

@@ -0,0 +1,11 @@
+<?php
+
+use Twig\Loader\ChainLoader;
+
+class_exists('Twig\Loader\ChainLoader');
+
+if (\false) {
+    class Twig_Loader_Chain extends ChainLoader
+    {
+    }
+}

system/libs/Twig/Twig/Loader/Filesystem.php

@@ -0,0 +1,11 @@
+<?php
+
+use Twig\Loader\FilesystemLoader;
+
+class_exists('Twig\Loader\FilesystemLoader');
+
+if (\false) {
+    class Twig_Loader_Filesystem extends FilesystemLoader
+    {
+    }
+}

system/libs/Twig/Twig/Loader/String.php

@@ -0,0 +1,63 @@
+<?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.
+ */
+
+use Twig\Loader\ExistsLoaderInterface;
+use Twig\Loader\LoaderInterface;
+use Twig\Loader\SourceContextLoaderInterface;
+use Twig\Source;
+
+@trigger_error('The Twig_Loader_String class is deprecated since version 1.18.1 and will be removed in 2.0. Use "Twig\Loader\ArrayLoader" instead or "Twig\Environment::createTemplate()".', E_USER_DEPRECATED);
+
+/**
+ * Loads a template from a string.
+ *
+ * This loader should NEVER be used. It only exists for Twig internal purposes.
+ *
+ * When using this loader with a cache mechanism, you should know that a new cache
+ * key is generated each time a template content "changes" (the cache key being the
+ * source code of the template). If you don't want to see your cache grows out of
+ * control, you need to take care of clearing the old cache file by yourself.
+ *
+ * @deprecated since 1.18.1 (to be removed in 2.0)
+ *
+ * @internal
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+class Twig_Loader_String implements LoaderInterface, ExistsLoaderInterface, SourceContextLoaderInterface
+{
+    public function getSource($name)
+    {
+        @trigger_error(sprintf('Calling "getSource" on "%s" is deprecated since 1.27. Use getSourceContext() instead.', \get_class($this)), E_USER_DEPRECATED);
+
+        return $name;
+    }
+
+    public function getSourceContext($name)
+    {
+        return new Source($name, $name);
+    }
+
+    public function exists($name)
+    {
+        return true;
+    }
+
+    public function getCacheKey($name)
+    {
+        return $name;
+    }
+
+    public function isFresh($name, $time)
+    {
+        return true;
+    }
+}