Changed a lot of pointer references to const (it's more correct and

fixes a weird problem), fixed a problem with JSON to DBC, a few other
fixes

mainwindow.cpp

@@ -729,7 +729,7 @@ void MainWindow::saveDecodedTextFile(QString filename)
     QFile *outFile = new QFile(filename);
     const QVector<CANFrame> *frames = model->getFilteredListReference();
 
-    unsigned char *data;
+    const unsigned char *data;
     int dataLen;
     const CANFrame *frame;
 
@@ -743,7 +743,7 @@ Data Bytes: 88 10 00 13 BB 00 06 00
     for (int c = 0; c < frames->count(); c++)
     {
         frame = &frames->at(c);
-        data = reinterpret_cast<unsigned char *>(frame->payload().data());
+        data = reinterpret_cast<const unsigned char *>(frame->payload().constData());
         dataLen = frame->payload().count();
 
         QString builderString;