Minimal PID controller primitives.
```toml
[dependencies]
use-pid = "0.0.1"
```
Use `use-pid` when you need a small PID controller primitive with explicit
proportional, integral, and derivative terms and no additional framework layer.
This crate is part of the `use-control` workspace. Depend on `use-control` when
you want the full facade.
This crate is experimental and may evolve while the workspace remains below
`0.3.0`.