refs #292, found during debugging

* const override of toQVariant
* missing getter / setters
* metaTuple
* improved toQString
* CClient::setCapability bug
* Fixed wrong ICAO check

src/blackmisc/avairporticao.cpp

@@ -71,6 +71,9 @@ namespace BlackMisc
             return TupleConverter<CAirportIcao>::jsonMembers();
         }
 
+        /*
+         * Unify ICAO code
+         */
         QString CAirportIcao::unifyAirportCode(const QString &icaoCode)
         {
             QString code = icaoCode.trimmed().toUpper();
@@ -79,6 +82,15 @@ namespace BlackMisc
             return (reg.exactMatch(code)) ? code : "";
         }
 
+        /*
+         * Valid ICAO designator?
+         */
+        bool CAirportIcao::isValidIcaoDesignator(const QString &icaoCode)
+        {
+            QString icao = unifyAirportCode(icaoCode);
+            return icao.length() == 4;
+        }
+
         /*
          * Equal?
          */