In place checking and repair of metadata attributes

[aphalo]

To simplify repair and validation of metadata attributes already assigned to spectral objects, add methods.

• for all attributes and spectral object classes:

  • Implement check_attributes() for checking the validity of attributes present in spectral objects to complement copy_attributes().

• for geocodes:

  • Add method repairWhenMeasured() to fix bad "where.measured" attributes by reference.