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
* 
	 * @param tag
	 *            the element tag
	 * @param name
	 *            the name attribute
	 * @param value
	 *            the text value
	 */
	protected void writeLongIndentText( String tag, String name, String value )
	{
		writer.startElement( tag );
		if ( name != null )
			writer.attribute( DesignSchemaConstants.NAME_ATTRIB, name );
		writer.indentLongText( value );
		writer.endElement( );
	}
	/**
	 * Writes the property of the given design element.
	 * 
	 * @param obj
	 *            the design element to write
	 * @param tag
	 *            the tag of the write
	 * @param propName
	 *            the property name
	 * @param cdata
	 *            whether the value should be written as CDATA.
	 */
	protected void writeProperty( DesignElement obj, String tag,
			String propName, boolean cdata )