Improvements to program output

[SimonVandeVyver]

During loop propagation, the program outputs 1000 times "Finished message loop iteration X / 1000". The output would be clearer if these lines overwrote each other.

[pverscha]

Thank you for the suggestion. Since multiple threads are outputting information at the same time, it is difficult to overwrite lines from the output. There are, however, some Python packages that handle this nicely and provide support for concurrent updates to progress bars printed to stdout.