Cleanup and simplification patches

[BartMassey]

Did a bunch of the stuff from my rewrite branch as small individual commits (except the rustfmt one is pretty big 🙂 ) so they can be reviewed separately. Please see the individual commits for the changes.

(Thanks for adding me as a committer. I still prefer to work through pull requests though: as you say, it's your codebase, plus review is always good.)

[pistacchio]

I think we where working onthe same things (more or less). I added you as collaborator in order to be able to request your review on the PR I was working on!

I'll wait for PR #5 to be done before reviewing this.

As a side note: if you're interested, I'd love your eyes on this: https://github.com/pistacchio/rcrpg-rust

[BartMassey]

Sigh. Apologies, wish I'd known you were going to do some of this.

Really want the rustdoc commit. The other stuff is pretty redundant with what I did. Moving rng construction into Maze::new() makes sense.

Do you want to rebase these two patchsets together or shall I?

[pistacchio]

This PR now conflicts with master. Can you please clean this up to only include what you think is not redundant with my own fixes? Thanks!

[BartMassey]

I'll get to it at some point. It's going to mostly be cherry-picking patches out of my branch. My rustfmt should probably be thrown away and done over: I regret doing it now. Let's get things stabilized and then run rustfmt.