std::str changes, and the way macros are expanded.

Now the grids are optimised so each column is only as wide as its longest file name. The method could do with some optimising, but at least it works.

Different types of user caches could come in the future...

- Prefer iter over into_iter where appropriate
- Cut down on cloning

I'm serious, the more functionality I can use external crates for, the better.

Feels good turning all that code into a dependency!

I can't complain, because the breaking changes were caused by my pull request...

With suggestions from helpful #rust folk. Thank you!

Yeah, I broke my own code again.

Also, re-use the stat result from directory-checking.

This finally fixes the issue where trying to list a file causes a crash. Also, tidy up some of the uses of references.

- Remove uses of to_string() on a &str where it wasn't necessary
- Use SendStr to reduce allocations further

I'm not sure if this a Rust change or something I've introduced...

What a strange bug to happen