Support dragging and dropping of files onto app icon

Tested on macos and windows.  Drag and drop files onto either the dock icon or task bar icon once SavvyCCAN is running

main.cpp

@@ -1,9 +1,30 @@
 #include "mainwindow.h"
 #include <QApplication>
 
+class SavvyCANApplication : public QApplication
+{
+public:
+    MainWindow *mainWindow;
+    
+    SavvyCANApplication(int &argc, char **argv) : QApplication(argc, argv)
+    {
+    }
+
+    bool event(QEvent *event) override
+    {
+        if (event->type() == QEvent::FileOpen)
+        {
+            QFileOpenEvent *openEvent = static_cast<QFileOpenEvent *>(event);
+            mainWindow->handleDroppedFile(openEvent->file());
+        }
+
+        return QApplication::event(event);
+    }
+};
+
 int main(int argc, char *argv[])
 {
-    QApplication a(argc, argv);
+    SavvyCANApplication a(argc, argv);
 
     //Add a local path for Qt extensions, to allow for per-application extensions.
     a.addLibraryPath("plugins");
@@ -14,7 +35,7 @@ int main(int argc, char *argv[])
     a.setOrganizationDomain("evtv.me");
     QSettings::setDefaultFormat(QSettings::IniFormat);
 
-    MainWindow w;
+    a.mainWindow = new MainWindow();
 
     QSettings settings;
     int fontSize = settings.value("Main/FontSize", 9).toUInt();
@@ -22,7 +43,11 @@ int main(int argc, char *argv[])
     sysFont.setPointSize(fontSize);
     a.setFont(sysFont);
 
-    w.show();
+    a.mainWindow->show();
 
-    return a.exec();
+    int retCode = a.exec();
+    
+    delete a.mainWindow; a.mainWindow = NULL;
+    
+    return retCode;
 }