Add optional goal compass

[aishwd94]

An optional observation variable that points to the direction of the first goal rather than the orientation of the agent. The observable image in itself provides very little information for the agent to advance ( even if a human looked at the partially observable grid, they would have to rely on mere random guessing ). This need for the agent to take arbitrary steps to discover the grid further could be removed.
The direction can be simply the tan inverse of the difference of goal and current position:
dir_radians = numpy.arctan( (goal[1] - agent_pos[1]) / (goal[0] - agent_pos[0]) )

[maximecb]

Hi @minuteman1911

I think the cleanest way to do this might be to create an ObservationWrapper that adds this information to the info object.

There are already a few wrappers implemented in wrappers.py. If you'd like to implement this, I will accept a pull request.

[aishwd94]

Hi,
Thank you for your response! I'll submit a pull request.