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* Switch to PyJWT 2 and Python 3.6, cleaning up Python 2 relics (321 - 323)
* Allow preselection of channels and dumps upon katdal.open() to save time and memory (324)
* Allow user to select fields, scans and antennas in mvftoms (269)
* Support h5py 3.0 string handling in MVF3 (331)
* Refactor requirement files to remove recursive dependencies (329)