Add exception for serializing unserializable exceptions.

The SimpleSAML_Error_Exception class is a base class for serializable
exceptions. This patch adds SimpleSAML_Error_UnserializableException.
That class saves some of the information from an Exception and saves it
in an serializable exception.

git-svn-id: https://simplesamlphp.googlecode.com/svn/trunk@1564 44740490-163a-0410-bde0-09ae8108e29a

lib/SimpleSAML/Error/UnserializableException.php

+<?php
+
+/**
+ * Class for saving normal exceptions for serialization.
+ *
+ * This class is used by the SimpleSAML_Auth_State class when it needs
+ * to serialize an exception which doesn't subclass the
+ * SimpleSAML_Error_Exception class.
+ *
+ * It creates a new exception which contains the backtrace and message
+ * of the original exception.
+ *
+ * @package simpleSAMLphp
+ * @version $Id$
+ */
+class SimpleSAML_Error_UnserializableException extends SimpleSAML_Error_Exception {
+
+	public function __construct(Exception $original) {
+
+		$msg = get_class($original) . ': ' . $original->getMessage();
+		$code = $original->getCode();
+		parent::__construct($msg, $code);
+
+		$this->setBacktrace(SimpleSAML_Utilities::buildBacktrace($original));
+	}
+
+}
\ No newline at end of file