Description:
------------
Hi there,
I need to use PHP's URL rewriter for sessions with a built-in web client that cannot support cookies but also has 'special' HREF attributes on certain tags, such as href="*title".

While I admit that this is certainly quite an edge case, I could certainly see many uses for a callback for the PHP URL rewriter function (passes original URL and what PHP would rewrite the URL to, function returns new URL to replace the original), for validation and such :-)

Test script:
---------------
<?php
function url_footobar($original, $rewritten) {
    return str_replace('foo', 'bar', $rewritten);
}
url_rewriter_callback('url_footobar()');
?>
<a href="http://foo.com/foo.php">foo</a>

Expected result:
----------------
<a href="http://bar.com/bar.php">foo</a>