Add DisCoCirc tutorial on babi task

[ouissal-moumou]

This adds a tutorial showing how to use a DisCoCirc model for solving the babi6 task.

This is the first version of the tutorial. Ignore any errors that might stem from previous unsuccessful runs of the experiments.

[dimkart]

@ouissal-moumou Are there two separate notebooks? Can we just merge everything into one? If not, we will need a main index file that joins the two parts.

@neiljdo FYI

[neiljdo]

@dimkart it seems the two notebooks can be merged into one to improve the flow of the tutorial - the second notebook is just the training step + result visualization. Doing so also makes this tutorial similar to the existing ones.

Also, the tutorial might benefit from some refactoring - I can work on this incrementally.

[dimkart]

@neiljdo Great, and if you think you can merge the two notebooks let's do this.

[DNA386]

Overall good start on the tutorials, but there's a few places that could do with simplification to make the tutorial clearer. Some general comments to keep in mind:

• try to keep your explanatory sentences shorter. some are very verbose, which can make it harder to follow what you mean.
• in general it is more 'pythonic' to use list/dict comprehensions where you can rather than for loops. (at least in my opinion) this will typically make your code easier to follow too. I've tried to suggest the simplifications in places I think it would help, but feel free to disagree!

[neiljdo]

Closing this as PR #63 now supersedes this.