Dev 0 2

TODO:

• manage tomo nexus file format -> will be done in another PR (!9 (merged))
• add distance property
• add energy property
• rework MetricSystem
• get utils function to get properties with units:
  • cannot be set in properties (because properties)
  • we could:
    • get one getter per property
    • let the user manage it when calling it
    • get a 'util function': get_property_with_unit (property, unit) which will call the correct property and cast it
    • for now I would vote for the the second one, can be discussed -> we decided with @paleo to create getters with unit one needed