clean gallery shortcode

I’ve modify the gallery shortcode to do a better and a cleaner job

here’s the code
wp-includes/media.php line 384

function gallery_shortcode($attr) {
	global $post;

	// Allow plugins/themes to override the default gallery template.
	$output = apply_filters('post_gallery', '', $attr);
	if ( $output != '' )
		return $output;

	// We're trusting author input, so let's at least make sure it looks like a valid orderby statement
	if ( isset( $attr['orderby'] ) ) {
		$attr['orderby'] = sanitize_sql_orderby( $attr['orderby'] );
		if ( !$attr['orderby'] )
			unset( $attr['orderby'] );
	}

	extract(shortcode_atts(array(
		'order'      => 'ASC',
		'orderby'    => 'menu_order ID',
		'id'         => $post->ID,
		'itemtag'    => '',
		'icontag'    => '',
		'captiontag' => '',
		'columns'    => 4,
		'size'       => 'thumbnail',
	), $attr));

	$id = intval($id);
	$attachments = get_children( array('post_parent' => $id, 'post_status' => 'inherit', 'post_type' => 'attachment', 'post_mime_type' => 'image', 'order' => $order, 'orderby' => $orderby) );

	if ( empty($attachments) )
		return '';

	if ( is_feed() ) {
		$output = "\n";
		foreach ( $attachments as $id => $attachment )
			$output .= wp_get_attachment_link($id, $size, true) . "\n";
		return $output;
	}

	$listtag = tag_escape($listtag);
	$itemtag = tag_escape($itemtag);
	$captiontag = tag_escape($captiontag);
	$columns = intval($columns);
	$itemwidth = $columns > 0 ? floor(100/$columns) : 100;

	foreach ( $attachments as $id => $attachment ) {
		$link = wp_get_attachment_image($id, $size, true);
		$output .= '<a href="'.wp_get_attachment_url($id).'">'.$link.'</a>';
	}

	$output .= "<br style='clear: both;' />";

	return $output;
}