Suggestion: Allow Jayse objects inside JsonObject.fromJson()

[timovandeput]

To create nested structures of JSON objects, it makes sense to build them using JsonObject.fromJson(...).

But when I try to put any JsonValue inside such structure, parsing throws an exception like: "Invalid argument(s): Unknown JSON value type: JsonString".

Please consider allowing the (re-)use of JsonValue instances inside JsonObject.fromJson(), so wrapping earlier parsed JSON does not require repackaging.

Thank you for the otherwise amazing library!