Bug 182680 Use feature of new Aggregation framework of Data Engine.
DataEngine will implement new aggregation framework in 2.2.0RC0. After the implementation is finished Engine should go ahead to use new column bindings in definition of map/highlight.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/adapter/ExpressionUtil.java
{
	private static final String TOTAL_PREFIX = "TOTAL_COLUMN_";
	private int totalColumnSuffix = 0;
	public ITotalExprBindings prepareTotalExpressions( List exprs )
	{
		return prepareTotalExpressions( exprs, null );
	}
	/**
	 * 
	 * @param exprs
	 * @return
	 */
	public ITotalExprBindings prepareTotalExpressions( List exprs, String groupName )