refs #403 add default constructors to CAvionicsBase and CPhysicalQuantity

The rationale behind this is that QtMetaType complains if there
is no default constructor.

src/blackmisc/aviation/avionicsbase.h

@@ -23,6 +23,10 @@ namespace BlackMisc
         protected:
             QString m_name; //!< name of the unit
 
+            //! Default constructor
+            //! \todo Remove as part of MS' CValueObject refactoring
+            CAvionicsBase() : m_name("empty") {}
+
             //! \brief Constructor
             CAvionicsBase(const QString &name) : m_name(name) {}