Changes to integrate into WSJT-X build system

A  separate install  of the  portaudio  library is  now required,  see
"doc/building on MS Windows.txt" for a suitable recipe.

The map65  code base  is still  MS Windows specific  in some  areas so
don't expect successful builds on Linux or macOS yet.

map65/main.cpp

@@ -7,10 +7,22 @@
 
 #include "mainwindow.h"
 
+static QtMessageHandler default_message_handler;
+
+void my_message_handler (QtMsgType type, QMessageLogContext const& context, QString const& msg)
+{
+  // Handle the messages!
+
+  // Call the default handler.
+  (*default_message_handler) (type, context, msg);
+}
+
 int main(int argc, char *argv[])
 {
-    QApplication a(argc, argv);
-    MainWindow w;
-    w.show();
-    return a.exec();
+  default_message_handler = qInstallMessageHandler (my_message_handler);
+
+  QApplication a {argc, argv};
+  MainWindow w;
+  w.show ();
+  return a.exec ();
 }