Port the examples from packed_simd

[workingjubilee]

packed_simd hosts various examples in its repo, featuring classics like

• Aobench
• Dot Product
• Fannkuch Redux
• Mandelbrot
• Matrix Inverse
• N-Body
• Options Pricing
• Slice Sum
• Spectral Norm
• Stencil
• Triangle Xform

We've already had users come up with code (in spite of not even being published to crates.io), so obviously we're doing something right in terms of making a decently intuitive API, but we should port some of these to the current API to provide more practical working examples, and also tacitly a bench suite, in this repo or another. That or we should figure out why we're not doing so.

[calebzulawski]

Great idea, definitely a good way to ensure our API is actually usable.

[miguelraz]

Should every example be packaged in a mini-crate? or would a single runnable for Rust Playground be a better idea?

[calebzulawski]

Cargo supports examples in the examples/ directory, which can be automatically built and tested: https://doc.rust-lang.org/cargo/guide/project-layout.html)

I would put them each in their own file in there.