Update project to use latest stable and 2018

[jacobgardner]

Since 1.30 proc-macro has been in stable rust and also includes things such as proper span information on tokens. I don't think there anything left in this crate that needs nightly any more which should allow more developers to use this. We also don't need macro_use either.

With 2018 edition there's a bunch of additional path cleanup we can do in this crate. I probably missed some of the fixes, but it cleans up a lot of the boilerplate at the top of the program.

Let me know if there's any issues.

[anp]

Hi! Thanks so much for the PR :D.

I had a couple of minor nits about glob imports (I know I committed the original sin, but by sending PRs you've demonstrated this code may be valuable and therefore I was wrong to do so!), otherwise this is awesome.

[jacobgardner]

I removed all the globs but the prelude one in there. I reverted back to using #[macro_use] for some of the crates because the macros had other macro dependencies which was making the dependency list quite long.

This issue will go away when the crates start using $crate::macro_name, but for now, I thought this made the most sense.

[anp]

Thank you!