refs #192, enable value objects for JSON:

* from/toJson methods
* jsonMembers where applicable

src/blackmisc/nwuser.h

@@ -120,9 +120,18 @@ namespace BlackMisc
             //! \copydoc CValueObject::getValueHash()
             virtual uint getValueHash() const override;
 
+            //! \copydoc CValueObject::toJson
+            virtual QJsonObject toJson() const override;
+
+            //! \copydoc CValueObject::fromJson
+            void fromJson(const QJsonObject &json) override;
+
             //! \brief Register metadata
             static void registerMetadata();
 
+            //! \brief Members
+            static const QStringList &jsonMembers();
+
             /*!
              * This and another user exchange missing data.
              * This user has priority and overrides first.