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
{
		PropertyDefn nameProp = (ElementPropertyDefn) obj.getDefn( )
				.getProperty( resourceName );
		assert nameProp != null;
		Object value = obj.getLocalProperty( getModule( ), nameProp.getName( ) );
		String xml = nameProp.getXmlValue( getModule( ), value );
		PropertyDefn keyProp = (ElementPropertyDefn) obj.getDefn( )
				.getProperty( resourceKey );
		assert keyProp != null;
		value = obj.getLocalProperty( getModule( ), keyProp.getName( ) );
		String xmlKey = keyProp.getXmlValue( getModule( ), value );
		if ( xmlKey == null && xml == null )
			return;
		if ( nameProp.getTypeCode( ) == IPropertyType.HTML_TYPE )
		{
			writeResouceKey( DesignSchemaConstants.HTML_PROPERTY_TAG,
					resourceName, xmlKey, xml, cdata );
		}
		else
		{
			writeResouceKey( DesignSchemaConstants.TEXT_PROPERTY_TAG,
					resourceName, xmlKey, xml, cdata );
		}
	}
	/**
	 * Writes the resource key of structure.
	 * 
	 * @param struct
	 *            the structure
	 * @param resourceKey