Segmentation-models-pytorch

Updates
- Pytorch image models (timm) version upgrade to 0.9.2

Updates
- Added Apple's Mobile One encoder from [repo](https://github.com/apple/ml-mobileone) (use `encoder_name="mobileone_s{0..4}"`).
- Pytorch image models (timm) version upgrade to 0.6.12 (500+ encoders available)
- Minor typo fixes and docs updates

Breaking changes
- Minimum Python version 3.6 -> 3.7

Thanks VadimLevin, kevinpl07, Abd-elr4hman

Updates
- Added Mix Vision Transformer encoder from SegFormer [[official code](https://github.com/NVlabs/SegFormer)] [[paper](https://arxiv.org/abs/2105.15203)]. Use argument `encoder_name="mit_b0"` (or mit_b1..b5) to create a model.
- Minor typo fixes and docs updates

Updates
- Added `smp.metrics` module with different metrics based on confusion matrix, see [docs](https://smp.readthedocs.io/en/latest/metrics.html)
- Added new [notebook](https://github.com/qubvel/segmentation_models.pytorch/blob/master/examples/binary_segmentation_intro.ipynb) with training example using pytorch-lightning 
- Improved handling of incorrect input image size error (checking image size is 2^n)
- Codebase refactoring and style checks (black, flake8)
- Minor typo fixes and bug fixes

Breaking changes
- `utils` module is going to be deprecated, if you still need it import it manually `from segmentation_models_pytorch import utils`

Thanks a lot for all contributors!

Updates
- Universal timm encoder. 400+ pretrained encoders from [timm](https://github.com/rwightman/pytorch-image-models) available with `tu-` prefix. List of available encoders [here](https://smp.readthedocs.io/en/latest/encoders_timm.html).
- Minor fixes and improvements.

Updates
- New architecture: MANet (310)
- New encoders from `timm`: mobilenetv3 (355) and gernet (344)
- New loss functions in `smp.losses` module (`smp.utils.losses` would be deprecated in future versions)
- New pretrained weight initialization for first convolution if `in_channels > 3`
- Updated timm version (0.4.12)
- Bug fixes and docs improvement

Thanks to azkalot1 JulienMaille originlake Kupchanski loopdigga96 zurk nmerty ludics Vozf markson14 and others!