Annotation/file-driven serialization test/bugfixes
JSON files are now automatically annotated with the type of the object. Also new annotated versions of string-serialization API
Moved to ordered_json, so as to provide a canonical representation of the objects.
Implemented some file-driven external serialization tests. Each test is run through most of the API, to check that it works.
Still am not testing failure cases in the test suite, that should perhaps be done as well.
The tests uncovered some bugs, which have now been fixed.
The file utilities have also been rewritten, improved, and added to the public headers.