* Support to use `indices` to specify which samples to evaluate.
* Add KFoldDataset wrapper
* Rename 'K' to 'num_splits' accroding to sklearn
* Add `kfold-cross-valid.py`
* Add unit tests
* Add help doc and docstring
* Add API inference in the docs and fix readthedocs config.
* Replace some relative link in docs.
* Format docstring for reStructuredText syntax.
* Fix vit paper link
* Fix docstring of `show_results` function in `BaseClassifier`.