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/driver/DimensionAxis.java
* row.
	 * 
	 * @throws OLAPException
	 */
	public void beforeFirst( ) throws OLAPException
	{
		this.edgeInfo.dim_beforeFirst( dimAxisIndex );
	}
	/**
	 * 
	 * @param position
	 * @throws OLAPException
	 */
	public void setPosition( long position ) throws OLAPException
	{
		this.edgeInfo.dim_setPosition( dimAxisIndex, position );
	}
	/**
	 * Returns the cursor in current position.
	 * 
	 * @return the cursor in current position.
	 * @throws OLAPException
	 */
	public long getPosition( ) throws OLAPException
	{
		return this.edgeInfo.dim_getPosition( dimAxisIndex );
	}
	/**
	 * Closes the result set and releases all resources.
	 * @throws OLAPException