streamline the python-user interface of the parametrizer-wrapper

- allow constructors to be filled with the same stuff like setters
- rename various setters from 'set' to something which is not a
  python keyword
- add some python properties for your convenience
  (e.g. use source.ID instead of .s(g)etSourceID)
- add more tests
- add update methods for PySource and PySourceCatalog
- add getSourceIDs method for PySourceCatalog
- add exceptions for mismatch between IDs in source-PyMeasurement
  and catalog dictionaries
- add a warning-option to PySourceCatalog.updateSources() to throw an
  exception if one or more source IDs are already present
make use of new cparametrizer features in sofia, also do PEP8 style