Introduce fmt and clippy early on as "recommended practices"

Having taught Rust multiple classes plus advising substantial number of projects, I noticed many, especially C++ developers undervalue the importance of `cargo fmt`, compiler warnings, and clippy warnings.

I think it would be good to introduce good "Rust hygiene" practices early on, and make sure to stress the importance of them.

Important points:
* most Rust projects standardize on `cargo fmt`, and Rust developers expect the code to follow the same rules
* automate `fmt` on save (available in both VS Code and IntelliJ)
* don't fight `cargo fmt` - if unhappy with the results, insert additional variables/statements to keep code easier to read
* don't ignore compiler warnings - they hide bugs. Use `#[allow(...)]` in the few edge cases.
* use `cargo clippy` to improve you Rust-foo.