author types are missing when authors are invisible

Hi,
if one selects biblio_contributors as invisible for a certain type, so that it is moved into the other_fields array, the author types are missing. That's because the function is called as

_biblio_contributor_widget($form['other_fields'],...

but in biblio_contributor_widget() the $tid is tried to fetch from the form by

$tid = (isset($node['biblio_type']))?$node['biblio_type']:$form['biblio_type']['#default_value'];

But $form['biblio_type'] is not available if we passed $form['other_fields'], as $form

The attached patch adds an optional $tid parameter and passes it when calling _biblio_contributor_widget with the subform. If $tid is passed, it is not calculated again.

cu,
Frank