Enhancements

we needed the ability to work with JSON-arrays generated and consumed by google-gson (A Java library to convert JSON to Java objects and vice-versa) in stored procedures, so we decided to enhance the json_array type.
As we handle small objects we added the "to_string" method to the json_array and json_object to encapsulate the CLOB-handling, but we are not sure about "the right" way to avoid invalid return values.