Use u32::reverse_bits to reverse bits

[nico-abram]

I wanted to try running dev/cmp to bench but I ran into #89

I ran the perf example on bwv_542_fuge.ogg about 10 times with and without the change. This is a horrible way of doing this and probably meaningless, but I wanted to at least get some numbers before opening this issue. I would not really expect a perf regression from this, but just in case I feel like it should be benchmarked.

Max/min with change: 1.0420328 s/1.0198687 s
Max/min without change: 1.0231534 s/1.1075205 s

[nico-abram]

ubuntu-latest seems to be running rust 1.36, reverse_bits is available since 1.37

I can update the MSRV in the readme (Which says it is 1.36) for the PR, although I don't know if changing that for the next release would actually be acceptable. If it isn't, should this PR just be left open until it is?

[est31]

Thanks this is a good catch! As you already found out, lewton currently has a MSRV of 1.36.0. I'm not sure I want to increase it for this small improvement alone, especially as it requires a semver breaking update. Especially there is still a sizeable chunk of downloads for versions prior to 0.10.

[nico-abram]

Understandable! Should this PR be closed, or can it be left open until a time you consider bumping the MSRV?

[est31]

@nico-abram your choice!

[nico-abram]

Leaving it open is fine by me

[est31]

As an alternative to leaving this PR open, one could change it to add a TODO comment, similar to what I've done in c059882

[roderickvd]

I think Ubuntu is on Rust >= 1.47 now so this could go in?