Modules/Segmentation/Algorithms/itkContourExtractor2DImageFilter.h should be superseded by itk's own itk::ContourExtractor2DImageFilter. The itk version has a lot more functionality, especially for multilabel contour extraction and is already present in itk. The code in the Segmentation folder seems to have been copied from a previous itk version.
Unless anyone has objections, i.e.