New parallel PyTorchRL library based on this one

[giadefa]

@ikostrikov We have developped a new library starting from this one. We have submitted now what we think that is a practically final version.

It is still based on pytorch but has two differences:

• It is scalable on multi GPUs and multi nodes and
• It provides a modular approach which helps in developping multiple algorithms, both on-policy and off-policy, We provide several.

Few years ago we used your PPO implementation to get second position in this challenge from Unity: https://blogs.unity3d.com/2019/08/07/announcing-the-obstacle-tower-challenge-winners-and-open-source-release/

But we felt we would have won if the library was parallel, so here it is PyTorchRL:
https://github.com/PyTorchRL/pytorchrl

and the paper:
https://arxiv.org/abs/2007.02622

The docs:
https://pytorchrl.readthedocs.io/en/latest/

I think that this is relevant for people who would like to try multiple algorithms or scale it up. We would be happy to work with you somehow if you still keen in this. In any case, I hope that this message is useful for you and everyone else, but feel free to close it, if it's not.

Best,
Gianni