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
* @param propName
	 *            the property name
	 */
	protected void propertyCDATA( DesignElement obj, String propName )
	{
		writeProperty( obj, null, propName, true );
	}
	/**
	 * Writes one property entry of an structure as CDATA.
	 * 
	 * @param structure
	 *            the structure
	 * @param memberName
	 *            the member name
	 */
	protected void propertyCDATA( IStructure structure, String memberName )
	{
		writeProperty( structure, null, memberName, true, false );
	}
	/**
	 * Writes one property entry of an structure without member name.
	 * 
	 * @param structure
	 *            the structure
	 * @param memberName
	 *            the member name
	 */
	protected void propertyWithoutName( IStructure structure, String memberName )
	{
		writeProperty( structure, null, memberName, false, true );