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/impl/aggregation/sort/AggregationSortHelper.java
* (non-Javadoc)
	 * @see org.eclipse.birt.data.engine.olap.data.api.IAggregationResultRow#getLevelMembers()
	 */
	public Member[] getLevelMembers( )
	{
		return this.levelMember;
	}
	/*
	 * (non-Javadoc)
	 * @see org.eclipse.birt.data.engine.olap.data.api.IAggregationResultRow#setAggregationValues(java.lang.Object[])
	 */
	public void setAggregationValues( Object[] aggregationValues )
	{
		this.aggr = aggregationValues;
	}
	/*
	 * (non-Javadoc)
	 * @see org.eclipse.birt.data.engine.olap.data.api.IAggregationResultRow#setLevelMembers(org.eclipse.birt.data.engine.olap.data.impl.dimension.Member[])
	 */
	public void setLevelMembers( Member[] levelMembers )
	{
		this.levelMember = levelMembers;
	}
}
/**
 * This implementation of IAggregationResultRow only stores aggregation values, without
 * store any level info.
 *
 */
class AggrValueOnlyResultRow implements IStructure, IAggregationResultRow