refs #314, fromQVariant / location of toQVariant

* renamed fromQVariant to convertFromQVariant, the "from" methods imply the object is changed (fromJson, fromString ..)
* implemented fromQVariant - changing the object by QVariant
* moved toQVariant into PQ template
* free function setFromQVariant

src/blackmisc/geoearthangle.h

@@ -111,6 +111,12 @@ namespace BlackMisc
             //! \copydoc CValueObject::toIcon
             CIcon toIcon() const override;
 
+            //! \copydoc CValueObject::toQVariant
+            virtual QVariant toQVariant() const override { return QVariant::fromValue(*derived()); }
+
+            //! \copydoc CValueObject::fromQVariant
+            virtual void fromQVariant(const QVariant &variant) override { BlackMisc::setFromQVariant(derived(), variant); }
+
             //! Register metadata
             static void registerMetadata();