* 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/phar-io/version/src/BuildMetaData.php

@@ -0,0 +1,28 @@
+<?php declare(strict_types = 1);
+/*
+ * This file is part of PharIo\Version.
+ *
+ * (c) Arne Blankerts <arne@blankerts.de>, Sebastian Heuer <sebastian@phpeople.de>, Sebastian Bergmann <sebastian@phpunit.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+namespace PharIo\Version;
+
+class BuildMetaData {
+
+    /** @var string */
+    private $value;
+
+    public function __construct(string $value) {
+        $this->value = $value;
+    }
+
+    public function asString(): string {
+        return $this->value;
+    }
+
+    public function equals(BuildMetaData $other): bool {
+        return $this->asString() === $other->asString();
+    }
+}