"maxlen" in parlai.core.torch_agent.History actually does nothing

https://github.com/facebookresearch/ParlAI/blob/c7f4b64df1a706464c053f036fe2ff38600f4558/parlai/core/torch_agent.py#L209

I think the description

• maxlen – sets the maximum number of tunrs

should be changed to

• size – sets the maximum number of tunrs