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
}
	}
	/**
	 * Writes the resource key as CDATA.
	 * 
	 * @param obj
	 *            the design element
	 * @param resourceKey
	 *            the resource key value
	 * @param resourceValue
	 *            the user-visible resource value
	 */
	protected void resourceKeyCDATA( DesignElement obj, String resourceKey,
			String resourceValue )
	{
		resourceKey( obj, resourceKey, resourceValue, true );
	}
	/**
	 * Writes the entry.
	 * 
	 * @param tag
	 *            the tag to write
	 * @param name
	 *            the property name or member name
	 * @param value
	 *            the xml value
	 * @param cdata
	 *            whether the values should be written as CDATA.
	 */
	protected void writeEntry( String tag, String name, String value,