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
if ( name != null )
			writer.attribute( DesignSchemaConstants.NAME_ATTRIB, name );
		writer.indentLongText( value );
		writer.endElement( );
	}
	/**
	 * Writes the property of the given design element.
	 * 
	 * @param obj
	 *            the design element to write
	 * @param tag
	 *            the tag of the write
	 * @param propName
	 *            the property name
	 * @param cdata
	 *            whether the value should be written as CDATA.
	 */
	protected void writeProperty( DesignElement obj, String tag,
			String propName, boolean cdata )
	{
		PropertyDefn propDefn = obj.getPropertyDefn( propName );
		
		if ( propDefn == null )
			return;
		Object value = obj.getLocalProperty( getModule( ), propName );
		if ( value == null )
			return;
		String xml = propDefn.getXmlValue( getModule( ), value );
		if ( xml == null )
			return;