IvanUniTO

I am contributing this simple patch as one of the possible solutions to issue #87 Just bult a very simple pyproject .toml that uses [flit](https://flit.pypa.io/en/stable/index.html) as a build system for...

checkpoint file name is always the same by default. If you run multiple concurrent survtrace jobs (e.g. on different datasets) they will crash each other or even scramble numerical results...