GitLab

Summary:
Pull Request resolved: https://github.com/facebookresearch/d2go/pull/77

- Reimplement `get_cfg_diff_table` by reusing other utils
- Adding `reorder` option for `flatten_config_dict`
- Remove the legacy BC support for `ARCH_DEF`, including `str_wrap_fbnet_arch_def` and customized `merge_from_other_cfg`.
- Move `temp_defrost` from `utils.py` to `config.py`, this way there's no more namespace forwarding for `utils.py`
- Merge `test_config_utils.py` and `test_configs.py`

Reviewed By: zhanghang1989

Differential Revision: D28734493

fbshipit-source-id: 925f5944cf0e9019e4c54462e851ea16a5c94b8c