Updated decode highlighting and LotW user's data file management

Includes a new settings facility  with the highlighting being contrled
by a new model class and a  modified QListView to display the data for
editing. Edits  include enable and  disable check boxes,  a contextual
pop-up menu to adjust backkground and foreground colours.

Still   to   be   implemented    are   priorities   for   highlighting
categories. This  will be adjustable  by drag  and drop in  the Colors
settings panel, it is already implemented by the priority order has no
effect on highlighting of decodes yet.

The LotW  users data file fetch  and time since user's  last upload is
now controled from the settings dialog.

This change also drops support for Qt versions before 5.5 so that many
workarounds for earlier versions can be removed.

Debug trace is slightly modified to make better use of the Qt built in
facilities to format and synchronize cross thread messaging.

main.cpp

@@ -17,13 +17,10 @@
 #include <QStandardPaths>
 #include <QStringList>
 #include <QLockFile>
-#include <QStack>
 #include <QSplashScreen>
 
-#if QT_VERSION >= 0x050200
 #include <QCommandLineParser>
 #include <QCommandLineOption>
-#endif
 
 #include "revision_utils.hpp"
 #include "MetaDataRegistry.hpp"
@@ -54,38 +51,12 @@ namespace
       qsrand (seed);            // this is good for rand() as well
     }
   } seeding;
-
-  class MessageTimestamper
-  {
-  public:
-    MessageTimestamper ()
-    {
-      prior_handlers_.push (qInstallMessageHandler (message_handler));
-    }
-    ~MessageTimestamper ()
-    {
-      if (prior_handlers_.size ()) qInstallMessageHandler (prior_handlers_.pop ());
-    }
-
-  private:
-    static void message_handler (QtMsgType type, QMessageLogContext const& context, QString const& msg)
-    {
-      QtMessageHandler handler {prior_handlers_.top ()};
-      if (handler)
-        {
-          handler (type, context,
-                   QDateTime::currentDateTimeUtc ().toString ("yy-MM-ddTHH:mm:ss.zzzZ: ") + msg);
-        }
-    }
-    static QStack<QtMessageHandler> prior_handlers_;
-  };
-  QStack<QtMessageHandler> MessageTimestamper::prior_handlers_;
 }
 
 int main(int argc, char *argv[])
 {
   // Add timestamps to all debug messages
-  MessageTimestamper message_timestamper;
+  qSetMessagePattern ("[%{time yyyyMMdd HH:mm:ss.zzz t} %{if-debug}D%{endif}%{if-info}I%{endif}%{if-warning}W%{endif}%{if-critical}C%{endif}%{if-fatal}F%{endif}] %{message}");
 
   init_random_seed ();
 
@@ -108,7 +79,6 @@ int main(int argc, char *argv[])
       a.setApplicationName ("WSJT-X");
       a.setApplicationVersion (version ());
 
-#if QT_VERSION >= 0x050200
       QCommandLineParser parser;
       parser.setApplicationDescription ("\n" PROJECT_SUMMARY_DESCRIPTION);
       auto help_option = parser.addHelpOption ();
@@ -210,11 +180,11 @@ int main(int argc, char *argv[])
                 }
             }
         }
-#endif
 
 #if WSJT_QDEBUG_TO_FILE
       // Open a trace file
       TraceFile trace_file {temp_dir.absoluteFilePath (a.applicationName () + "_trace.log")};
+      qSetMessagePattern ("[%{time yyyyMMdd HH:mm:ss.zzz t} %{if-debug}D%{endif}%{if-info}I%{endif}%{if-warning}W%{endif}%{if-critical}C%{endif}%{if-fatal}F%{endif}] %{file}:%{line} - %{message}");
       qDebug () << program_title (revision ()) + " - Program startup";
 #endif