Bug 141064 Remove group level data binding
This bug covers the engine part of the task to remove group level data binding. After the hange, all binding expressions will be defined on the table level, and each binding expression will have an AggregateOn field to explicitly define the group level for that expression.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/data/dte/ReportQueryBuilder.java
* @param direction
		 *            "asc" or "desc" string
		 * @return integer value defined in <code>ISortDefn</code>
		 */
		protected int parseSortDirection( String direction )
		{
			if ( "asc".equals( direction ) ) 
				return ISortDefinition.SORT_ASC;
			if ( "desc".equals( direction ) ) 
				return ISortDefinition.SORT_DESC;
			assert false;
			return 0;
		}
		/**
		 * Transfers old expressions to column bindings and new expression.
		 * 
		 * @param item
		 *            the report design.
		 */
		private void transferExpressions( ReportItemDesign item )
		{
			IBaseTransform trans = getTransform();
			if (trans != null)
			{
				ITotalExprBindings totalExpressionBindings = getNewExpressionBindings( item );
				addNewColumnBindings( trans, totalExpressionBindings );
				replaceOldExpressions( item, totalExpressionBindings );
			}
		}
	}