Add fromDateTime() to create version 1 UUIDs from DateTime instances

Fixes #28

src/Exception/TimeSourceException.php

@@ -0,0 +1,24 @@
+<?php
+
+/**
+ * This file is part of the ramsey/uuid library
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ *
+ * @copyright Copyright (c) Ben Ramsey <ben@benramsey.com>
+ * @license http://opensource.org/licenses/MIT MIT
+ */
+
+declare(strict_types=1);
+
+namespace Ramsey\Uuid\Exception;
+
+use RuntimeException as PhpRuntimeException;
+
+/**
+ * Thrown to indicate that the source of time encountered an error
+ */
+class TimeSourceException extends PhpRuntimeException
+{
+}