Added SwinIR and new features to readme

* Add LDSR Upscaling

added correct torchvision version to default torch install command

request from Shangchen Zhou

--opt-split-attention now on by default for torch.cuda, off for others (cpu and MPS; because the option does not work there according to reports)

This reverts commit 9035afba.

This reverts commit 8d1d64f9.