Added device error message to file open error messages

Thanks to  Mike W9MDB for contributing  this as a patch.  Also added a
few more in elsewhere.

git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@4883 ab8295b8-cf94-4d9e-aec4-7959e3be5d79

astro.cpp

@@ -145,7 +145,7 @@ void Astro::astroUpdate(QDateTime t, QString mygrid, QString hisgrid,
   if (!f.open (QIODevice::WriteOnly | QIODevice::Text))
     {
     QMessageBox mb;
-    mb.setText ("Cannot open \"" + f.fileName () + "\".");
+    mb.setText ("Cannot open \"" + f.fileName () + "\" for writing:" + f.errorString ());
     mb.exec();
     return;
   }