Bug 179737 The MeasureHandle should be able to provide data type info
We are now allow user input expression as measure expression. However this brings difficulties in determine the data type of a measure expression evaluation result. We need MeasureHandle to be enhanced to include the data type info. Please note that data type "any" is not accepted.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/writer/ModuleWriter.java
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
			writer.text( xml );
		writer.endElement( );
	}
	/**
	 * Writes the structure list, each of which has only one member.
	 * 
	 * @param obj
	 *            the design element
	 * @param propName
	 *            the name of the list property
	 * @param memberName
	 *            the name of the member in structure
	 */
	protected void writeSimpleStructureList( DesignElement obj,
			String propName, String memberName )
	{
		PropertyDefn prop = (ElementPropertyDefn) obj.getDefn( ).getProperty(
				propName );
		assert prop != null;