code cleanup for loading signup properties into the $node object

The code currently laboriously puts each property from the {signup} table into the $node object.
I think the following is a cleaner approach, easier to read, and easier to maintain in future:

        unset($signup['nid']); // because we don't need to set the nid!
        foreach ($signup as $key => $signup_data) {
          $node->{"signup_$key"} = $signup_data;
        }