URL Normalizer: Normalize URLs according to RFC 3986

Syntax based normalization of URI's

This normalises URI's based on the specification RFC 3986 
http://www.apps.ietf.org/rfc/rfc3986.html

Example usage:
<code>
require_once 'URLNormalizer.php';

$url = 'eXAMPLE://a/./b/../b/%63/%7bfoo%7d';
$un = new URLNormalizer();
$un->setUrl( $url );
echo $un->normalize();

// result: "example://a/b/c/%7Bfoo%7D"
</code>

TODO:

Add further scheme-based normalization steps, as detailed in section 6.2.3 of the RFC.