Pid Rs Versions Save

This version 4 release of pid-rs comes with a new builder-pattern syntax for the controller, as well as more examples and content in docs.rs. The major breaking change is how the controller is defined and (optionally) modified. Before it used to be along the lines of:

// Create a controller
let mut my_controller = Pid::new(10.0, 0.0, 0.0, 100.0, 100.0, 100.0, 100.0, 15.0);

// Change a value
pid.ki = 2.5;
pid.i_limit = 20.0;

And with this new release, the syntax has been changed to:

// Create a controller
let mut pid = Pid::new(15.0, 100.0);
pid.p(10.0, 100.0).i(1.0, 100.0).d(2.0, 100.0);

// Change a value
pid.i(2.5, 20.0)

This new release is available on crates.io and this repository as always.

Support for three-term output limit.