Add std flags to allow disabling std.

[alex-quach-arc-boats]

No description provided.

[kylecarow]

Thanks for the PR! I think there is quite a lot of code throughout the crate that uses std, e.g. many of the error variants allocate Strings. There are probably clever ways to rewrite many of these allocations, and it would make sense to include much existing code as part of a std feature.

I take it this PR was made for itertools dependency reasons? I believe there are other dependencies in this crate with default std features, ndarray for example.

I'll be happy to take a deeper look at this when I return from vacation next week!

[alex-quach-arc-boats]

Thanks for taking a look! I had slapped this together with the Github UI, just thinking that I needed to transitively pass the std feature to the dependency crates. But after trying to build it locally I realized what you said which is that the crate itself needs std, so tbh at that point I gave up and rewrote the 2D lerping with ChatGPT.

Mostly I just need lerping and grid/lookup table-type interpolation in a embedded environment, and as far as I can could tell, all the crates in this category assume std.

Thanks again for taking a look!