configuration file

• add option --darks --flats --projections, --return
• add those options to the settings file.
• add a way to provide a configuration file and overwrite the existing settings file
• create a simple function to generate automatically a configuration file
  • question: is this function always create the same configuration file or does it generate values from the settings.py ??? Or maybe create two functions / option: a quick-start --generic and a quick-start--local or a common-start / local-start ???