* Defaults to return tuple in all backbones.
* Compat downstream of swin transformer.
* Support tuple input for multi label head and stacked head.
* Fix backbone unit tests for tuple output.
* Add downstream inference unit tests for mmdet.
* Update gitignore
* Add unit tests for `return_tuple` option
* Add unit tests for head input tuple.
* Add warning in `simple_test`
* Add TIMMBackbone return tuple.
* Modify timm backbone unit test.
* 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
Ezra-Yu
Zhicheng Chen
Ma Zerun