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
{
		CrosstabCellHandle cellHandle = levelView.addSubTotal( measures,
				functions );
		if ( cellHandle == null )
		{
			return;
		}
		CrosstabUIHelper.CreateSubTotalLabel( levelView, cellHandle );
	}
	private List findMeasureViewHandleList( List list )
	{
		List retValue = new ArrayList( );
		for ( int i = 0; i < list.size( ); i++ )
		{
			retValue.add( findMeasureViewHandle( (MeasureHandle) list.get( i ) ) );
		}
		return retValue;
	}
	private MeasureViewHandle findMeasureViewHandle( MeasureHandle handle )
	{
		return levelHandle.getCrosstab( )
				.getMeasure( handle.getQualifiedName( ) );
	}
	private LevelViewHandle findLevelViewHandle( LevelHandle handle )
	{
		DimensionViewHandle viewHandle = getDimensionViewHandle( );
		return viewHandle.getLevel( handle.getQualifiedName( ) );
		
	}
	static class SubOpration