Vocal-remover

Note
- Update model architecture
- Update the pre-trained model

Note
- Update training parameters
- Update a post-processing parameter
- Update `Usage` section of the README

Note
- Hotfix to the training script
- Split `--max_reduction_rate` option into `--reduction_rate` and `--reduction_level`

Note
- Hotfix to the training script

Note
- Implement train/val splitting based on subdirectories
- Update training parameters

Note
- Fix normalization of complex spectrograms
- Make Test Time Augmentation (TTA) optional
- Support for training on CPU

If you want to improve the vocal removal quality with TTA, use the `--tta` option.

CPU
python inference.py --input path/to/an/audio/file --tta

GPU
python inference.py --input path/to/an/audio/file --tta --gpu 0