- New setup_logging.py module to set the global logger handler
- Use new princess feature to run setup_logging.py before executing notebook
- copy setup_logging.py to the CAL_WORKING_DIRECTORY for more simplicity in accessing the file from anywhere (should be enough for reproducability?).
- LOGGING:
  - WARNINGs to warnings.logs
  - ERRORs to errors.logs
  - ALL console logs are not using any special format on purpose

Addresses https://git.xfel.eu/gitlab/detectors/pycalibration/merge_requests/464#note_228864

This metadata file subsumes the old retrieved constants YAML file.  The commit includes some refactoring centered around pathlib.