* add phpunit as a dev dependency

* add some basic tests for UrlHelper::rewrite_relative()
 * fix UrlHelper::rewrite_relative() to work better on non-absolute
   relative URL paths

vendor/nikic/php-parser/lib/PhpParser/Node/AttributeGroup.php

@@ -0,0 +1,29 @@
+<?php declare(strict_types=1);
+
+namespace PhpParser\Node;
+
+use PhpParser\Node;
+use PhpParser\NodeAbstract;
+
+class AttributeGroup extends NodeAbstract
+{
+    /** @var Attribute[] Attributes */
+    public $attrs;
+
+    /**
+     * @param Attribute[] $attrs PHP attributes
+     * @param array $attributes Additional node attributes
+     */
+    public function __construct(array $attrs, array $attributes = []) {
+        $this->attributes = $attributes;
+        $this->attrs = $attrs;
+    }
+
+    public function getSubNodeNames() : array {
+        return ['attrs'];
+    }
+
+    public function getType() : string {
+        return 'AttributeGroup';
+    }
+}