Prints the OPML page for the feed.
$variables: An associative array containing:
function theme_aggregator_page_opml($variables) {
$feeds = $variables['feeds'];
drupal_add_http_header('Content-Type', 'text/xml; charset=utf-8');
$output = "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n";
$output .= "<opml version=\"1.1\">\n";
$output .= "<head>\n";
$output .= '<title>' . check_plain(variable_get('site_name', 'Drupal')) . "</title>\n";
$output .= '<dateModified>' . gmdate(DATE_RFC2822, REQUEST_TIME) . "</dateModified>\n";
$output .= "</head>\n";
$output .= "<body>\n";
foreach ($feeds as $feed) {
$output .= '<outline text="' . check_plain($feed->title) . '" xmlUrl="' . check_url($feed->url) . "\" />\n";
}
$output .= "</body>\n";
$output .= "</opml>\n";
print $output;
}