Pytorch-segmentation-models-trainer

- Bug fixes when inputs are RGBA images;
- Bug fixes on frame field model with models other than U-Net;
- Bug fixes on FrameFieldResultCallback (all black image fixed).

- Added frame field training image visualization callback.

Bug fixes on missing entrypoints and mask process execution.

Polygoniztion by Frame Field Learning features

- FrameField dataset
- FrameField Learning
- Polygonization

Bug fixes on image callback when Pytorch Lightning DDP is used.

Bug fixes when Pytorch Lightning DDP is used.