Fix most of `clippy::pedantic`

Part of #7.

This MR has fixed many of the clippy::pedantic lints, in alphabetical order.

Due to the huge refactor involved in the latest commit (49a917ba), the clippy::pedantic lints will be fixed in multiple MRs.

There are no interesting commits, just a lot of code being moved around.

requested review from @lgaeher

Thanks!

merged