BUG 0000 Grid fields not rendered when values are null

- When the grid values don't have a value for a field this field is not rendered
- Add validation to send empty values for grid fields

gulliver/system/class.xmlform.php

@@ -4569,6 +4569,7 @@ class xmlformTemplate extends Smarty
       $result [$k] = G::replaceDataField ( $form->fields [$k]->label, $form->values );
       if (! is_array ( $value )) {
         if ($form->type == 'grid') {
+          $therow = isset($form->values[$form->name]) ? count($form->values[$form->name]) : $therow;
           $aAux = array ();
          // $index = ($therow >count ( $form->owner->values [$form->name] ))? $therow : count($form->owner->values [$form->name] );
           for($i = 0; $i < $therow; $i ++) {