* Support HRNet
* Add HRNet configs
* Fix a bug in backward
* Add configs and update docs.
* Not use bias in conv before batch norm
* Defaults to use `norm_eval=False`
* Add unit tests and support out_channels in HRFuseScales
* Update checkpoint path
* Update docstring.
* Remove incorrect files
* Improve according to comments
* Refactor unit tests folder structure.
* Remove label smooth and Vit test in `test_classifiers.py`
* Rename test_utils in dataset to test_dataset_utils
* Split test_models/test_utils/test_utils.py to multiple sub files.
* Add unit tests of classifiers and heads
* Use patch context manager.
* Add unit test of `is_tracing`, and add warning in `is_tracing` if torch
verison is smaller than 1.6.0