Committing all changes to the copy constraints section at once

[ethorhil]

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[ethorhil]

I fixed the copy constraints now in the sense that it is now closer to how it would actually be in the protocol.

I think we have to make our minds up on the goals: we are doing many things that are conceptually correct but slightly simpler than in the actual protocol. If the goal is to use the components to put everything together in the end, we will have to re-write basically everything.

Some examples from the copy constraints section:
- v1 and v2 are in practice generated differently
- polynomials are over fields and require a whole lot of machinery around that
- If we use roots of unity there will be some changes
- The check we are performing here (abc = a'*b'*c') doesnt actually appear like that in the protocol. They use additional tricks.

Similar small simplifications are basically everywhere in the repo that I looked at...

That said, I think the existing tutorial can fulfill the goal of teaching people unfamiliar with ZKP the individual concepts.

Let me know what you think...