Page and feed rewrite part 1

So here's a starting point for the page and feed code.

The page is now a column sortable table with pagination. I'm not sold on the viability of this approach, but it's a start. Obviously not all the columns are needed, and we need to generate the tokenized message and have it, too.

As for the feeds, I propose that every module implements its own formatter for feed items, like this:

  if (count($activities) > 0) {
    foreach ($activities as $activity) {
      $function = $activity['module']. '_format_rss_item';
      if (function_exists($function)) {
        // each module gets a chance to build its own feed item.
        // They should use the $activity to prepare variables and
        // call format_rss_item($title, $link, $item_text, $extra);
        $items .= $function($activity);
      }
    }
  }