Incompatibility with scikit-image 0.17.1 and higher

In version 0.17.1 of scikit-image, an API change was made where register_translation was moved from skimage.feature to skimage. See commit 4502. This breaks importation of fpd.fpd_processing and fpd.synthetic_data. Downgrading to scikit-image version 0.16.2 restores functionality.

Either the scikit-image dependency should be pinned in the setup file or a check on the scikit-image version number should be implemented at the import statements for register_translation in fpd.fpd_processing and fpd.synthetic_data. The latter is probably better in case Anaconda overrides the pip installed scikit-image at any point.