FacesetRelighter fixes and improvements:

now you have 3 ways:
1) define light directions manually (not for google colab)
   watch demo https://youtu.be/79xz7yEO5Jw
2) relight faceset with one random direction
3) relight faceset with predefined 8 directions

nnlib/nnlib.py

@@ -144,6 +144,7 @@ NLayerDiscriminator = nnlib.NLayerDiscriminator
         if 'CUDA_VISIBLE_DEVICES' in os.environ.keys():
             os.environ.pop('CUDA_VISIBLE_DEVICES')
 
+        io.log_info ("Using PyTorch backend.")
         import torch
         nnlib.torch = torch