Get rid of warnings

[nleroy917]

My local environment (rust-analyzer + clippy) shows over 170 "problems"/warnings in the codebase. These can be small formatting/idiomatic style changes proposed by clippy down to things like a variable being mut when it doesn't need to be.

It would be nice to get rid of these and suppress clippy warnings when it makes sense because it makes it harder to debug and detect issues when there are so many of these small warnings.