Heuristic PID Tuning [Feature Request]

[Bradw-17]

This is a shot in the dark, but if possible, incorporating PID tuning heuristics such as the Cohen-Coon method would be an awesome addition. Trying to interpolate the graphs by eye may be challenging, so adding a heuristic mathematical formula may benefit some. Perhaps a "Suggested PID values" displayed below the users set PID values. I'm no programmer, so I don't exactly have the knowledge to incorporate this into Plasmatree. But I think it would be really helpful, especially to get a base reference to fine-tune from.