M4 Emergency stop during calibration

[Carson_Barry]

fitness is 1/average error

New user experience and first cut!

Thanks to @dlang for fitness explantion: fitness = 1/average error where average error is looking at each point and measuring the difference between the belt lengths that it thinks it should have at that point with the calculated frame size and the belt length measurements that it got at that point. Yes, larger frames typically have larger errors and lower fitness.