Generate better formatted Rust code

[csmulhern]

There are no behavioral changes in the PR. This simply updates the Rust generator to produce better formatted code, with the following changes:

1. Whitespace is added between function definitions.
2. Newline insertions are better factored / tracked, so you don't end up with two consecutive empty lines.
3. Code inside mod blocks is properly indented.
4. #[inline] annotations have been moved below function documentation, which is the expected style.

The first commit contains the relevant changes.
The second commit simply regenerates all the example code.

It would be easiest to review the commits separately.

[csmulhern]

@jtdavis777 it looks like you've been reviewing recent PRs for this project. I have a few more Rust style cleanups I would love to do. They aren't functional changes, so should be pretty straightforward to review. Can I send them your way?

[jtdavis777]

Sure I can add this to the docket. I am not a rust dev at all but am happy to look this over.

[csmulhern]

Great, thank you!