Add addGroupBy method for DataTable

Author: jcheron

Ajax/semantic/widgets/base/InstanceViewer.php

@@ -449,6 +449,10 @@ public function getGroupByFields() {
 	public function setGroupByFields($groupByFields) {
 		$this->groupByFields = $groupByFields;
 	}
+	
+	public function addGroupBy($groupByField){
+		$this->groupByFields[]=$groupByField;
+	}
 
 	public function getGroupByFieldsCount() {
 		if (is_array($this->groupByFields)) {

Ajax/semantic/widgets/datatable/DataTable.php

@@ -711,6 +711,13 @@ public function getGroupByFields() {
 	public function setGroupByFields($_groupByFields) {
 		$this->_instanceViewer->setGroupByFields($_groupByFields);
 	}
+	
+	public function addGroupBy($index){
+		$index = $this->_getIndex($index);
+		if ($index !== false) {
+			$this->_instanceViewer->addGroupBy($index);
+		}
+	}
 
 	/**
 	 *