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
.getPropertyHandle( IAccessControlModel.ROLES_PROP )
				.getStringValue( ) );
		assertEquals( "level value1; level value2", valueAccessControl 
				.getPropertyHandle( IValueAccessControlModel.VALUES_PROP )
				.getStringValue( ) );
		assertEquals( DesignChoiceConstants.ACCESS_PERMISSION_DISALLOW,
				valueAccessControl.getPermission( ) );
		
		propHandle = cube
				.getPropertyHandle( TabularCubeHandle.MEASURE_GROUPS_PROP );
		assertEquals( 1, propHandle.getContentCount( ) );
		assertEquals( 1, cube
				.getContentCount( TabularCubeHandle.MEASURE_GROUPS_PROP ) );
		MeasureGroupHandle measureGroup = (MeasureGroupHandle) propHandle
				.getContent( 0 );
		assertEquals( measureGroup, cube.getContent(
				TabularCubeHandle.MEASURE_GROUPS_PROP, 0 ) );
		assertEquals( "testMeasureGroup", measureGroup.getName( ) ); 
		
		assertEquals( measureGroup, cube.getDefaultMeasureGroup( ) );
		propHandle = measureGroup
				.getPropertyHandle( MeasureGroupHandle.MEASURES_PROP );
		
		MeasureHandle measure = (MeasureHandle) propHandle.getContent( 0 );
		assertEquals( "testMeasure", measure.getName( ) ); 
		assertEquals( "column", measure.getMeasureExpression( ) ); 
		assertEquals( DesignChoiceConstants.MEASURE_FUNCTION_MIN, measure
				.getFunction( ) );
		assertFalse( measure.isCalculated( ) );
		assertEquals( DesignChoiceConstants.COLUMN_DATA_TYPE_STRING, measure