i.pytorch.predict: New module to apply pytorch model to imagery group

[ninsbl]

First version ready to merge: Covers:

• [x] add Makefile for i.pytorch
• [x] implement clipping to inner tile
• [x] implement multiple output channels
• [x] add more output_config (unit, description, semantic_label, ...)
• [x] CPU and GPU processing
• [x] generic handling of pytorch models
• [x] cleanup function for temporary data

And avoids using 3rd party code

Need to:

• [x] add test case
• [ ] more linting