Bug 189363 The aggregation of table should be start with sigma symbol
Description: Follow the spec, after specify a aggregation on a table, the aggregation should be represented by starting with the sigma symbol
xtab/org.eclipse.birt.report.item.crosstab.ui/src/org/eclipse/birt/report/item/crosstab/internal/ui/editors/action/AddSubTotalAction.java
{
			int oriSize = oriOperation.getMeasures( ).size( );
			int newSize = newOperation.getMeasures( ).size( );
			if ( oriSize != newSize )
			{
				levelHandle.getCrosstab( )
						.removeGrandTotal( getDimensionViewHandle( ).getAxisType( ) );
				addGrandTotal( levelHandle.getCrosstab( ),
						getDimensionViewHandle( ).getAxisType( ),
						newOperation.getFunctions( ),
						findMeasureViewHandleList( newOperation.getMeasures( ) ) );
				return;
			}
			for ( int i = 0; i < oriSize; i++ )
			{
				if ( oriOperation.getMeasures( ).get( i ) != newOperation.getMeasures( )
						.get( i ) )
				{
					levelHandle.getCrosstab( )
							.removeGrandTotal( getDimensionViewHandle( ).getAxisType( ) );
					addGrandTotal( levelHandle.getCrosstab( ),
							getDimensionViewHandle( ).getAxisType( ),
							newOperation.getFunctions( ),
							findMeasureViewHandleList( newOperation.getMeasures( ) ) );
					return;
				}
			}
			for ( int i = 0; i < oriSize; i++ )
			{
				if ( !oriOperation.getFunctions( )