Added context information to Hamlib interface exception messages.

Enhanced TransceiverBase  error exception  type to allow  for language
translatable messages.

git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@4033 ab8295b8-cf94-4d9e-aec4-7959e3be5d79

TransceiverBase.hpp

@@ -3,12 +3,12 @@
 
 #include <stdexcept>
 
+#include <QString>
+
 #include "Transceiver.hpp"
 
 #include "pimpl_h.hpp"
 
-class QString;
-
 //
 // Base Transceiver Implementation
 //
@@ -84,7 +84,8 @@ protected:
   struct error
     : public std::runtime_error
   {
-    error (char const * msg) : std::runtime_error (msg) {}
+    error (char const * const msg) : std::runtime_error (msg) {}
+    error (QString const& msg) : std::runtime_error (msg.toStdString ()) {}
   };
 
   // Template methods that sub classes implement to do what they need to do.