fixed step_by change rust issue #27741

[william20111]

Ignoring the rustfmt stuff, its just adding the step by feature as its changed. And it takes usize now so added a cast to that.

Rust - rust-lang/rust#27741

#![feature(iterator_step_by)]

[mehcode]

I'd say we should just change the underlying types to usize rather than have the cast.

[william20111]

Makes much more sense. Still getting to know the crate so might be better suited to somebody more comfortable with the code.

[zslayton]

@william20111 Thanks!

@mehcode It is my understanding that usize should be reserved for data that is dependent on the architecture (i.e. pointers/indexes). Some guidelines are discussed here. All of the values being represented in this crate have a very limited domain: 0-59 seconds/minutes, 0-23 hours, 0-31 days of the month, etc. I could safely represent them each as a single u8. In fact, I probably should since I'm storing several trees with dozens of values each and that would be a nice space savings.

I'm going to merge this PR. Please open an issue if you'd like to discuss it further.

[mehcode]

@zslayton Makes sense.