Autoformat crate

[tiziano88]

This was done by running the cargo fmt command on the crate.

[AtheMathmo]

This looks fine to me (but it is a lot of code to check over).

It looks like the library may be getting some actual maintenance soon ( #199 ) so if that involves some refactor I'll leave it up to those parties to decide whether these formatting improvements should come before or after.

[tiziano88]

Thanks for the reply! The format PR was in fact a prerequisite for more refactorings that I would like to send to you soon, if there is interest. I think you should check the code, or run the same command yourself and check there are no extraneous diffs, it should be a quick one. Anyway let me know what you prefer, I would like it for rusty-machine to become the de facto ML crate in Rust!