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.tests/test/org/eclipse/birt/report/model/parser/TabularCubeParserTest.java
* <li>if one new value access control is added to the level in the cube1.
	 * Value access controls on the level cube2 will be copies to the level of
	 * cube1 first.
	 * </ul>
	 * 
	 * @throws Exception
	 */
	public void testExtends( ) throws Exception
	{
		openDesign( FILE_NAME_EXTENDS );
		assertNotNull( designHandle );
		
		libraryHandle = designHandle.getLibrary( "Lib1" ); 
		TabularCubeHandle cube = (TabularCubeHandle) libraryHandle
				.findCube( "testCube" ); 
		TabularCubeHandle newCube = (TabularCubeHandle) designHandle
				.getElementFactory( ).newElementFrom( cube, null );
		designHandle.getCubes( ).add( newCube );
		save( );
		assertTrue( compareFile( "TabularCubeParserTest_extends_golden_1.xml" ) ); 
		AccessControlHandle control = designHandle.getElementFactory( )
				.newAccessControl( );
		control.addUserName( "new user name 1" ); 
		newCube.add( ICubeModel.ACCESS_CONTROLS_PROP, control );
		save( );
		assertTrue( compareFile( "TabularCubeParserTest_extends_golden_2.xml" ) ); 
		designHandle.getCommandStack( ).undo( );
		LevelHandle level = designHandle.findLevel( "testDimension1/testLevel" ); 
		ValueAccessControlHandle valueAccess = designHandle.getElementFactory( )
				.newValueAccessControl( );