* feat(Tests): added basic unit tests for walk_forward_train_test()
* fix(Tests): inherit from BaseEstimator, fix index problems in walk_forward_train_test
* fix(WalkForward): predictions were mistakenly removed, oops
* fix(WalkForward): mistakenly re-assiging model
* feat(Eval): added format_data_for_backtest()
* feat(Data): added many configurable parameters to load_files to reduce boilerplate and prepare for HPO
* feat(Core): added walk forward method of training/testing
* fix(Model): remove the unnecessary softmax activation from the keras models
* feat(Core): added walk_forward_train_test()
* feat: Started implementing pytorch-forecasting.
* feat(Forecasting): pytorch-forecasting scaffolding is now working, added narrow data format, fixed missing `time` column index name
Co-authored-by: Daniel Szemerey <szemy2@gmail.com>