Cleanup: toFormattedQString was not really used and just redirecting toQString

* marked deprecated
* and replaced by toQString

src/blackcore/application.cpp

@@ -1282,7 +1282,7 @@ namespace BlackCore
         if (msgs.isEmpty()) { return false; }
         if (!msgs.hasErrorMessages())  { return false; }
         CApplication::cmdLineErrorMessage(
-            msgs.toFormattedQString(true)
+            msgs.toQString(true)
         );
         return false;
     }