* feat: add a PID controller implementation
* feat: add small rigid-body utilities + test interpolation test
* fix: make scrolling weaker on macos
* feat: add the option to use the PID controller in the character controller demo.
* feat: add a stateless PD controller
* feat(rapier_testbed): cleanup & support PidController in 2D too
* chore: add comments for the PD and PID controllers
* chore: update changelog
* feat: rename PidErrors to PdErrors which is more accurate
* fix cargo doc
* chore: remove dead code
* chore: make test module non-pub
* feat(rapier_testbed): autosave testbed configuration + add support for per-example parameters
* feat(rapier_testbed): also save the camera position
* feat(rapier_testbed): improve ergonomics of example-specific settings
* chore: cargo fmt
* chore(rapier_testbed): small UI ergonomics improvement
* chore(rapier_testbed): clippy fixes
- Fix the wrong codepath taken by the solver for contacts involving a collider without parent.
- Properly adress the non-linear treatment of the friction direction
- Simplify the sleeping strategy
- Add an impulse resolution multiplier