test groups don't return a type property

[rassilon]

This is similar but different from #22 since test groups never apparently returned a type property.

(and this library doesn't currently expose test plans/test groups)

[jmauersberger]

Bill, I think with PR #28 this issue could be solved. We added some generic "UnsupportedField" to get pass unsupported field types.

[rassilon]

in my C# port, I just ended up adding test plan/test group support.