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 ( propDefn.isEncryptable( ) )
		{
			IEncryptionHelper helper = MetaDataDictionary.getInstance( )
					.getEncryptionHelper( );
			xml = helper.encrypt( xml );
		}
		if ( tag == null )
			tag = ModelUtil.getTagByPropertyType( propDefn );
		if ( propDefn.getTypeCode( ) == IPropertyType.SCRIPT_TYPE )
			cdata = true;
		writeEntry( tag, propDefn.getName( ), xml, cdata );
	}
	/**
	 * Writes the structure memeber.
	 * 
	 * @param struct
	 *            the structure
	 * @param tag
	 *            the tag to write
	 * @param memberName
	 *            the member name
	 * @param cdata
	 *            whether the value should be written as CDATA
	 * @param withoutName
	 *            whether the property name should be written
	 */
	protected void writeProperty( IStructure struct, String tag,
			String memberName, boolean cdata, boolean withoutName )
	{
		StructureDefn structDefn = (StructureDefn) struct.getDefn( );