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/Node/IfNode.php

@@ -0,0 +1,72 @@
+<?php
+
+/*
+ * This file is part of Twig.
+ *
+ * (c) Fabien Potencier
+ * (c) Armin Ronacher
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Twig\Node;
+
+use Twig\Compiler;
+
+/**
+ * Represents an if node.
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+class IfNode extends Node
+{
+    public function __construct(\Twig_NodeInterface $tests, \Twig_NodeInterface $else = null, $lineno, $tag = null)
+    {
+        $nodes = ['tests' => $tests];
+        if (null !== $else) {
+            $nodes['else'] = $else;
+        }
+
+        parent::__construct($nodes, [], $lineno, $tag);
+    }
+
+    public function compile(Compiler $compiler)
+    {
+        $compiler->addDebugInfo($this);
+        for ($i = 0, $count = \count($this->getNode('tests')); $i < $count; $i += 2) {
+            if ($i > 0) {
+                $compiler
+                    ->outdent()
+                    ->write('} elseif (')
+                ;
+            } else {
+                $compiler
+                    ->write('if (')
+                ;
+            }
+
+            $compiler
+                ->subcompile($this->getNode('tests')->getNode($i))
+                ->raw(") {\n")
+                ->indent()
+                ->subcompile($this->getNode('tests')->getNode($i + 1))
+            ;
+        }
+
+        if ($this->hasNode('else')) {
+            $compiler
+                ->outdent()
+                ->write("} else {\n")
+                ->indent()
+                ->subcompile($this->getNode('else'))
+            ;
+        }
+
+        $compiler
+            ->outdent()
+            ->write("}\n");
+    }
+}
+
+class_alias('Twig\Node\IfNode', 'Twig_Node_If');