Gluonts

More shell fixes

- Add proper documentation strings.
- Fix the printed script name in help output.
- Add a `force-static` train parameter that forces the
creation of a static predictor from the expected
model location.

* Fixup of shell. (180)

* Re-added locate for Forecaster detection. (181)

* Minor fixes.

New features

* Adding option to rescale time series instead of clipping them, in artificial dataset generation (114)
* Include cdf method in distributions (120, 133)
* Add support for feat_dynamic_real field in DeepAREstimator (125)
* Add NPTS model (148)
* Added shell package (151, 156, 173)
* Custom seasonality for complex seasonal dataset (155)

Other changes

* Renamed time_granularity -> freq, time_freq -> freq (172, 173)
* Include safety check that catches infinite loops in transformations (139)

Fixes

* Fixes to paths (143)
* Fix default context_length in MQCNN and MQRNN estimators (167)

* Fixed problem with the `num_eval_samples` argument of `GluonPredictor.predict` (103)
* Fixed pydantic requirement, which was causing issues on Python 3.7 (108)

* fixed bugs in distributions (92)
* updated mxnet requirement (96)
* removed pandas warnings (97)

Issues fixed:
* Indexing issue in the RForecastPredictor (63)
* Issues with the LDS and Binned distributions (57 65 68)
* Hardcoded paths that affected Windows users (77)
* Worked around Pandas bug affecting some versions (79)
* Bug in the artificially generate datasets (83)
* Circular dependency issue (88)
* Removed FutureWarning complaints by Pandas (88)
* Bumped version requirement for rpy2 (89)