Bug 188578 Add "displayColumnName" on TabularLevel
Add Property "displayColumnName" on TabbularLevel and corresponding APIs on handle. Property Type: expression.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/writer/ModuleWriter.java
{
		if ( tree == null || tree.isEmpty( ) )
			return;
		List children = tree.getChildren( );
		for ( int i = 0; i < children.size( ); i++ )
		{
			ContentNode node = (ContentNode) children.get( i );
			writeContentNode( node );
		}
	}
	/**
	 * Writers the content node out to the file.
	 * 
	 * @param node
	 *            the content node to write out
	 */
	private void writeContentNode( ContentNode node )
	{
		String tagName = node.getName( );
		boolean isCdata = node.isCDATASection( );
		writer.startElement( tagName );
		
		Map attributes = node.getAttributes( );
		Iterator keys = attributes.keySet( ).iterator( );
		while ( keys.hasNext( ) )
		{
			String key = (String) keys.next( );
			String attr = (String) attributes.get( key );
			writer.attribute( key, attr );
		}