0.2.0

Bug fixes

• max_steps typo in TrainModel (can now continue training from a model checkpoint)
• API ordering mismatch for get_data_and_targets between online samplers and file samplers (now can run `EvaluateModel on both kinds of samplers)

Enhancements

• Significant improvements to the CLI/config file documentation: https://selene.flatironinstitute.org/overview/cli.html
• Allow callback handlers so that users can specify different kinds of metrics for training
• Support for training regression models using MatFileSampler: https://github.com/FunctionLab/selene/blob/master/tutorials/regression_mpra_example/regression_mpra_example.ipynb
• Allow saving new checkpoints after a certain number of steps in training (as opposed to overwriting the same one)
• Improved standard output logging for training
• Updated MatFileSampler so it no longer loads all data directly into memory if using an HDF5 file
• Allow users to have the option of loading the test set at the start of training, or (default) waiting until evaluation starts (if ops: [train, evaluate]).