Software PID controller
Currently in a slightly experimental state, if you are attaching this to anything can break, please sit right next to the emergency stop (and read the source).
Any change in behaviour (even bugfixes) in this will result in a major
version increase (0.a -> 0.a+1 or x.y.z -> x+1.0.0), so upgrading with ^
will not break your carefully set tunings.
Owes a great debt to: