Description:
------------
DateTime doesn't appear to use the default timezone (set either in php.ini or with date_default_timezone_set()).

It's currently BST in the UK and without calling setTimeZone() on a DateTime object, format() will produce a date/time that is one hour behind.

If setTimeZone() is called on a DateTime object then the date/time produced by format() is correct.

date() by itself uses the default timezone that has been set.  For consistency, DateTime should do also.

Test script:
---------------
<pre>
<?php
	date_default_timezone_set('Europe/London');

	$now = time();

	// Initialising with a timestamp, second DateTimeZone parameter would be ignored.
	$dt1 = new DateTime('@' . $now);
	echo 'DateTime->format()', "\t", $dt1->format('Y-m-d H:i:s T Z e');
	echo "\n";

	$dt2 = new DateTime('@' . $now);
	$dt2->setTimeZone(new DateTimeZone('Europe/London'));
	echo 'DateTime->format()', "\t", $dt2->format('Y-m-d H:i:s T Z e');
	
	echo "\n";
	echo 'date()', "\t\t\t", date('Y-m-d H:i:s T Z e', $now);
?>
<pre>

Expected result:
----------------
$dt1->format() should use Europe/London as the timezone and show the correct time for that timezone.

Actual result:
--------------
$dt1->format() shows +00:00 as the timezone and is an hour behind.