Off-Policy Algos - ACER, DDPG and SAC

[Riashat]

Would you be adding off-policy algorithms like ACER/SAC (which should be compatible for both cont action Mujoco and discrete action ALE tasks) and DDPG/TD3 for control to this repository any time soon?

Would be useful to have all these algos implemented within the same repo. I know this repo is being used as the standard codebase for a lot of papers these days.

[ikostrikov]

I'm planning to add SAC at some point. But there are some difficulties since it might be hard to make everything efficient within a single repo.