Fix formatting and add cargo fmt to CI

[Samyak2]

Some of the code isn't formatted. Can be fixed by running cargo fmt.

We should also enforce formatting by checking for formatting in CI. See this for an example.

[AugustoFKL]

Should be used the nightly feature?

It isn't a common-sense between projects, so I prefer to ask the main maintainer before doing stuff

In my own projects I usually use:

cargo clippy --all-targets --all-features -- -D warnings

and

cargo +nightly fmt --verbose -- --check

What do you think?

[Samyak2]

cargo clippy --all-targets --all-features -- -D warnings

This seems like a good default. Although, I would like to have a separate issue/PR for clippy. I'll create one now. (Edit: it's #25).

cargo +nightly fmt --verbose -- --check

What's the benefit of using nightly for cargo fmt? Also, what additional information would --verbose give that's needed in CI (the default output of cargo fmt --check lists diffs for files needing formatting, which is all one would need to know about formatting anyway)?

[AugustoFKL]

Sure, will do this in different PR's as requested.

About the nightly, it's not a convention. I use in my projects because, as some say, nightly supports more formatting options and produce prettier results.

But it's unstable. If you prefer to use the stable option (default), that's fine.

The verbose option is a personal pattern as well, will remove from the workflow

[Samyak2]

About the nightly, it's not a convention. I use in my projects because, as some say, nightly supports more formatting options and produce prettier results.

That makes sense. We should use nightly for spressolisp too.