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
writeEntry( tag, null, xml, cdata );
		else
			writeEntry( tag, memberName, xml, cdata );
	}
	/**
	 * Writes the resource key entry.
	 * 
	 * @param tagName
	 *            the tag name to write
	 * @param name
	 *            the property name of resource
	 * @param key
	 *            the resource key value
	 * @param xml
	 *            the resource value
	 * @param cdata
	 *            whether the resource value should be written as CDATA.
	 */
	protected void writeResouceKey( String tagName, String name, String key,
			String xml, boolean cdata )
	{
		
		if ( key == null && xml == null )
			return;
		writer.startElement( tagName );
		writer.attribute( DesignSchemaConstants.NAME_ATTRIB, name );
		writer.attribute( DesignSchemaConstants.KEY_ATTRIB, key );
		if ( cdata )
			writer.textCDATA( xml );
		else