Make repository pip-installable

[mihai-mc]

The repo cannot be installed by pip as-is. The only alternative would be to make this a submodule and import things as needed.

The fix, as a bare minimum, would solve this issue by adding a setup.py file to the repo

[nagadomi]

I do not consider this repository a library.
I keep breaking internal compatibility every day so the next update will screw everything up.

Which part do you want to use?
Currently, some modules are loadable with torch.hub.load.
I am careful not to break the compatibility of these interfaces, and if I break it, I will fix it.