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
* Writes the contents of a slot. The order is not the order in the slot
	 * while we first write the ancestor and then the derived ones. The contents
	 * are enclosed in an optional list tag.
	 * 
	 * @param obj
	 *            the container element
	 * @param slot
	 *            the slot to write
	 * @param tag
	 *            the optional list tag that encloses the list of contents
	 */
	protected void writeArrangedContents( DesignElement obj, int slot,
			String tag )
	{
		List list = obj.getSlot( slot ).getContents( );
		if ( list.isEmpty( ) )
			return;
		LinkedList newList = new LinkedList( );
		Iterator iter = list.iterator( );
		while ( iter.hasNext( ) )
		{
			DesignElement element = (DesignElement) iter.next( );
			DesignElement parent = element.getExtendsElement( );
			if ( !newList.contains( element ) )
			{
				newList.add( element );
			}
			if ( parent != null && list.contains( parent ) )
			{
				if ( !newList.contains( parent ) )