add: - Unit tests for 'Sample' and 'DataSet'.
change: - format/format_code ---> format/code, format/format_variant ---> format/variant ('--->' means renamed).
- sample/sample_type_description ---> sample/type_description, sample/sample_type_code ---> sample/type_code, sample/sample_code ---> sample/code.
- Integration tests adapted (they should not fail).

SVN: 5289