Pass hints to fst240sim, genfst240, and packjt77::pack77 on WSPR msgs

Due to  an ambiguity with  message encodings between 77-bit  QSO modes
and 50-bit  beacon modes with message  types 13.n3 4.0 and  0.6 a hint
needs to be  passed to ensure the right encoding  is emitted. The hint
only  effects  ambiguous messages,  others  will  be encoded  strictly
according to the message content.

widgets/mainwindow.cpp

@@ -3875,6 +3875,7 @@ void MainWindow::guiUpdate()
             char fst240msgbits[101];
             QString wmsg;
             if(m_mode=="FST240W") {
+              iwspr = 1;
               wmsg=WSPR_message();
               ba=wmsg.toLatin1();
               ba2msg(ba,message);