Breaking Changes
* Bump up minimal PyTorch version to 1.7.1
New features
* New dataset classes `ClassificationDataset`, `SegmentationDataset` for easy every-day use in Kaggle
* New losses: `FocalCosineLoss`, `BiTemperedLogisticLoss`, `SoftF1Loss`
* Support of new activations for `get_activation_block` (Silu, Softplus, Gelu)
* More encoders from timm package: NFNets, NFRegNet, HRNet, DPN
* `RocAucMetricCallback` for Catalyst
* `MultilabelAccuracyCallback` and `AccuracyCallback` with DDP support
Bugfixes
* Fix invalid prefix in catalyst registry to from `tbt` to `tbt.`