The Danielsson distance filter use pixel type of Offset<>, which does not have a specialized NumericTraits.

Encountered an issue with the `Image::GetNumberOfComponentsPerPixel` method not reporting the correct number of components with the results from `DanielssonDistanceMapImageFilter::VectorDistanceMap`. The resulting image has pixel type `Offset` which is missing a specialized `NumericTraits` to get the correct Length.

While the usage of Offset for a pixel type appears to be rather unusual, the proposed fix is to add the additional specialization of NumericTraits.