Added documentation and made clippy a lot more annoying.

[nishaq503]

During the conversation in this issue, you suggested some work on the "jank" in the crate. In this PR, I have started to address some of this. For now, I have:

• added documentation to pretty much everything that the lints warn about.
• made clippy a lot more annoying.
• addressed all clippy lints.

There are also some changes to function signatures as suggested by clippy. These include:

• Removing the Box<dyn Fn<...>> types with the simpler fn(...) types.
• Marking several const fn functions because they get evaluated at compile time, thus improving runtime performance.

I have ignored two clippy lints for the crate:

• Module name repeated in struct name: I think this is too pedantic a lint and would be a massive API change that I don't think you would want for now. Perhaps later.
• Functions with too many lines: I'm going to address this in a separate PR after spending some more time on the code.

[cmccomb]

Excellent PR! Thank you so much for your work on this!