unescape optimized

[dg]

Closes #32

[JanTvrdik]

Nice! The following seems to have slightly better worse-case:

preg_replace_callback(
    '#(%(?:' . substr(chunk_split(bin2hex($reserved), 2, '|'), 0, -1) . '))++#i',
    function($m) {
        return rawurlencode(strtoupper($m[0]));
    },
    $s
);

On the other hand – its slower for common inputs so probably not worth it.

[dg]

Reserved characters are rare, so probably not.