fix some clippy suggestions

[hellow554]

This contains mostly using of cast instead of as *const _ and the second thing is using the addr_of! macro for easier reading and avoiding possible UB (which isn't the case in any of the places I replaced the code).

[fpagliughi]

Hey, thanks so much for the PR!

Unfortunately, I don't think I can merge it as-is right now. I wasn't clear about the Minimum Supported Rust Version on the README, but I personally still need to support rustc v1.46 for a production system. (Sorry, that's my mistake). And I wouldn't want to push the required version forward just for readability issues.

It looks like addr_of_mut!() requires v1.51. Most of the other stuff looks good, and useful, so maybe we can split the difference and get most of these changes in.

BTW: What clippy lint did you use? My defaults didn't catch most of these things.

[hellow554]

I typically use cargo clippy -- -W clippy::pedantic -W clippy::nursery.
It gives a lot of warnings, especially docs, #[must_use] and const related stuff. But you can "disable" those with -A clippy::must_use_candidate for example. Give it a try ;)

I added a clippy toml and added the msrv of 1.46.0 as well as removed the addr_of! macro. Hope this is better :)

[fpagliughi]

Yeah. That sounds great. I will have a look over the weekend and get it merged. Thanks again!