Changes to Xorcism discussed in #1040

[snoyberg]

This should implement all of the changes discussed in #1040, barring one. Outside of a comment around impl Trait and removing the link to ExactSizeIterator, I did not modify the instructions in README.md. I believe with the change in tests to focus on munge_in_place first, the user will have sufficient ramp-up experience implementing the simpler exercise before jumping into the more complex one.

[coriolinus]

It's going to be at least another day until I can review this properly--we're well into New Year's Eve now, in my time zone at least--but I can say that the failing CI is because you edited README.md directly. Instead, do this:

• make an appropriate edit / insert into .meta/hints.md
• get configlet, probably with rust/bin/fetch-configlet
• run configlet generate . -o xorcism to regenerate the actual README

That should sort out the CI failure.

[snoyberg]

Thank you for the pointer! I'll try to get CI fixed. And no pressure at all from me, have a great New Year's.

[coriolinus]

Looks good! One nit remains that I'd like to see fixed before merging, but overall, I'm happy with this PR.

I have reviewed all changes made up to this point, and confirmed that it addresses all points raised in #1040. I have not yet run this locally to verify that bonus tests still pass (IIRC, our CI doesn't yet know how to handle those), but I see no reason why they wouldn't.

[snoyberg]

OK, the build is fixed. Let me know if you'd like me to rebase at this point.

[coriolinus]

Thanks for working on this! I have now verified locally that all tests, including feature tests, pass.

[snoyberg]

Awesome, thank you! I really appreciate all of the work you and the team put into the exercises here. It was invaluable when I was learning Rust, and has been a huge asset in my teaching.