Form submit handler for node_form().
Upon preview and final submission, we need to renumber poll choices and create a teaser output.
function poll_node_form_submit(&$form, &$form_state) {
// Renumber choices.
$form_state['values']['choice'] = array_values($form_state['values']['choice']);
$form_state['values']['teaser'] = poll_teaser((object) $form_state['values']);
}