/**
 * Returns the value of the selected radio button in the radio group
 * 
 * @param {radio Object} or {radio id} el
 * OR
 * @param {form Object} or {form id} el
 * @param {radio group name} radioGroup
 */
function $RF(el, radioGroup) {
	if($(el).type == 'radio') {
		var el = $(el).form;
		var radioGroup = $(el).name;
	} else if ($(el).tagName.toLowerCase() != 'form') {
		return false;
	}
	return $F($(el).getInputs('radio', radioGroup).find(
		function(re) {return re.checked;}
	));
}