New features
* The `ObjectSelector`, based on the `ObjectClassifier` for selecting objects of a given class. It produces an instance segmentation label image.
* The `ObjectMerger` has new options for features:
* `centroid_distance`,
* `mean_intensity_difference`,
* `standard_deviation_intensity_difference`,
* `area_difference`,
* `mean_max_distance_to_centroid_ratio_difference`
Potentially backwards breaking changes
* Internal refactoring in `ObjectClassifier` and `TableRowClassifier` may have caused backwards-compatibility breaking changes. This is not intentional. In case anyone experiences trouble, please create a github-issue and we'll fix it.