Add mutation testing strategy

[hackaugusto]

I was thinking on how to test our constraints automatically, to either verify that no constraints are missing, or to automatically find issues. And it occurred to me that mutation testing would be a good approach. The idea is to do the following:

• Run a program, say fib, and generate a trace as usual.
• Randomly modify one value in the trace.
• Try to prove the above, and check the proving fails.

The same can be done for verifying, by:

• Run a program and generate a proof
• Modify a random value in the proof
• Check the verification fails

If we write many minimal correct programs, each using a different instructions, and run the above strategy for each of said programs, we should have good coverage.

[Bisht13]

Hey @hackaugusto! Can I pick this up?

[hackaugusto]

@bobbinth ping. I'm not sure if you want to implement this or if there are conflicting plans.

@Bisht13 just a heads up, this is probably an involved task.

[Bisht13]

@hackaugusto I was scouting over the repo and wanted an issue to collaborate on, if you have anything on top of your mind, I'd love to pick it up, though I have no issue with picking this up as well.