Apply clippy::cast_lossless to make code more readable

[CrazyboyQCD]

Lint link.
Since there are plenty of as statments I think distinguishing between safe(lossless) conversion and coercion would make the code more readable.

Clippy should fix most of them:

cargo clippy --fix -- -D clippy::cast_lossless 

Left case(s) by clippy: link

[kkysen]

This might be useful; thanks for letting us know about it! That said, there are necessarily a lot of [_ as usize] casts and this might make that pretty noisy. We'll definitely think about it, though, as I agree it makes things more readable in a lot of cases.

[CrazyboyQCD]

This might be useful; thanks for letting us know about it! That said, there are necessarily a lot of [_ as usize] casts and this might make that pretty noisy. We'll definitely think about it, though, as I agree it makes things more readable in a lot of cases.

I tested it and found [_ as usize] will not be affected mentioned in the link above, so apply it will not mess that up.