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 ( prop.getTypeCode( ) == IPropertyType.XML_TYPE
						|| prop.getTypeCode( ) == IPropertyType.SCRIPT_TYPE )
					cdata = true;
				writeProperty( obj, ModelUtil.getTagByPropertyType( prop ),
						prop.getName( ), cdata );
			}
		}
	}
	/**
	 * Writes ODA exension properties.
	 * 
	 * @param obj
	 *            the ODA element to write
	 * @param provider
	 *            the extension provider
	 */
	private void writeOdaDummyProperties( DesignElement obj,
			ODAProvider provider )
	{
		assert provider instanceof OdaDummyProvider;
		OdaDummyProvider dummyProvider = (OdaDummyProvider) provider;
		
		ContentTree tree = dummyProvider.getContentTree( );
		writeContentTree( tree );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.elements.ElementVisitor#visitScriptDataSet(org.eclipse.birt.report.model.elements.ScriptDataSet)
	 */