Added ability to maintain bus and msg filters when clearing frames

mainwindow.h

@@ -99,6 +99,7 @@ private slots:
     void setupSendToLatestGraphWindow();
     void interpretToggled(bool);
     void overwriteToggled(bool);
+    void presistentFiltersToggled(bool state);
     void logReceivedFrame(CANConnection*, QVector<CANFrame>);
     void tickGUIUpdate();
     void toggleCapture();