Add walking controller comparison

[sibocw]

Description

See #190 #191 trying to move the walking controller benchmark code from nmf2-paper to flygym/exanokes

Does this address any currently open issues?

[list open issues here]

[sibocw]

@tkclam Thanks for pushing to this new branch

1. I renamed ColoredFly to ColorableFly because it doesn't color the fly by itself — it just allows the user to color the fly more easily.
2. I updated the docs and README a bit, could you please check if the information is correct?
3. I fixed a minor IO bug in your script (wrong relative path to the individual frames).
4. The aspect ratio of the images is a bit off (too narrow; see below). Do you know what might have caused this? Is it related to your recent changes?

controller_comparison.mp4

[tkclam]

I've just pushed a commit which should fix the aspect ratio