Switch path code to Camino

[sayrer]

I have some new features that use Camino, and I ended up replacing all of cargo-raze's path code with Camino while hunting down bugs. Cargo requires UTF-8 paths anyway, as the Camino docs state, so I think it's a reasonable change. Ok to PR?

https://github.com/camino-rs/camino

[illicitonion]

Works for me - see also #421 :)