Okay, problem finally Solved.
I had to rewrite all lines "containing motor.doClockwise...." also in PigpioStepperMotor.py
Great thanks to all who contributed.
I would like to know howto install screen. I have not found any information.I recently installed screen for Raspbian Buster using bash and it doesn't seem to work completely.
My wiringpi is already the newest version (2.44+1), So where do I find v 2.46 ?You need to upgrade to WiringPi 2.46 from 2.44.