NOBUG mod_surveypro: added some missing details to multiselect and checkbox item
Code update because of the outcome of the following autoconsistency test.
Each plugin must follow the:
if (method_exists(userform_get_filling_instructions)) {
    $this->isinitemform['hideinstructions'] = true;
} else {
    $this->isinitemform['hideinstructions'] = false;
}