make previous sw question configurable

booking.regn_form.inc

@@ -961,10 +961,11 @@ function booking_form($node, &$form_state, $inserting = FALSE)
     );
   }
   if (variable_get('booking_enable_previous_studyweeks', 0) == 1) {
+    $prev_sw_required_check = (variable_get('booking_require_previous_sw', 1) == 1) && $inserting; 
     $form['misc-areas']['booking_prev_sw_count'] = array(
       '#type' => 'select',
       '#title' => t("How many Study Weeks have you been to previously?"),
-      '#required' => FALSE,
+      '#required' => $prev_sw_required_check,
       '#default_value' => variable_get('booking_prev_sw_count', empty($data->booking_prev_sw_count) ? '' : $data->booking_prev_sw_count),
       '#options' => _get_previous_sw_options(),
     );