Bug 182895 Support sort on Level attribute.
Currently in OLAP engine we only support sort on level key value. We should go ahead to support sort on level attribute value.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/olap/data/api/CubeQueryExecutorHelper.java
resultSet[findMatchedResultSetIndex( resultSet, column )] = column;
		}
		if ( !this.rowSort.isEmpty( ) )
		{
			IAggregationResultSet row = AggrSortHelper.sort( this.rowSort,
					resultSet );
			resultSet[findMatchedResultSetIndex( resultSet, row )] = row;
		}
	}
	/**
	 * @param aggregations
	 * @param resultSet
	 * @param stopSign
	 * @throws IOException
	 * @throws DataException
	 * @throws BirtException
	 */
	private void applyAggrFilters( AggregationDefinition[] aggregations,
			IAggregationResultSet[] resultSet, StopSign stopSign )
			throws IOException, DataException, BirtException
	{
		if ( aggrFilterHelpers.isEmpty( ) == false )
		{
			List oldFilters = new ArrayList( levelFilters );
			AggregationFilterHelper filterHelper = new AggregationFilterHelper( cube,
					aggrFilterHelpers );
			
			List newFilters = filterHelper.generateLevelFilters( aggregations,
					resultSet );
			if ( newFilters == null )