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
writeUserPropertyDefns( obj );
		writeUserPropertyValues( obj );
		writeStyle( obj );
		writeContents( obj, ICellModel.CONTENT_SLOT, null );
		writer.endElement( );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.design.elements.DesignVisitor#visitGrid(org.eclipse.birt.report.model.design.elements.GridItem)
	 */
	public void visitGrid( GridItem obj )
	{
		
		boundColumnsMgr.dealGrid( obj, getModule( ) );
		writer.startElement( DesignSchemaConstants.GRID_TAG );
		super.visitGrid( obj );
		writeColumns( obj, IGridItemModel.COLUMN_SLOT );
		writeContents( obj, IGridItemModel.ROW_SLOT, null );
		writer.endElement( );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.design.elements.DesignVisitor#visitLine(org.eclipse.birt.report.model.design.elements.LineItem)
	 */
	public void visitLine( LineItem obj )
	{
		writer.startElement( DesignSchemaConstants.LINE_TAG );
		super.visitLine( obj );