Bug 200471 Add "need not sort for grouping" option in report item
Currently when Data engine proceeds groups, it always sorts the result set according to given group key.However that should not be necessary when the raw data is already sorted. So we'd like to add new options so that user can indicate whether should we sort the data before grouping. In model, we should allow user to set a "need not do sort for grouping" option to all the report element that can be grouped(table, list,etc.)
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/writer/ModuleWriter.java
( (DesignElement) iter.next( ) ).apply( this );
		}
		if ( tag != null )
			writer.endElement( );
	}
	/**
	 * Writes the contents of a slot. The contents are enclosed in an optional
	 * list tag.
	 * 
	 * @param obj
	 *            the container element
	 * @param slot
	 *            the slot to write
	 * @param tag
	 *            the optional list tag that encloses the list of contents
	 */
	protected void writeContents( DesignElement obj, int slot, String tag )
	{
		writeContents( new ContainerContext( obj, slot ), tag );
	}
	/**
	 * Writes the contents of an element property. The contents are enclosed in
	 * an optional list tag.
	 * 
	 * @param obj
	 *            the container element
	 * @param propName
	 *            the element property to write
	 * @param tag
	 *            the optional list tag that encloses the list of contents