configurable overlay color

src/mainwindow.h

@@ -29,6 +29,7 @@ public:
     void setAspect(char aspectIn);
     void setDebugMode(bool debugModeIn) {debugMode = debugModeIn;}
     void setFitAspectAxisToWindow(bool fitAspectAxisToWindowIn) { fitAspectAxisToWindow = fitAspectAxisToWindowIn; }
+    void setOverlayHexRGB(QString overlayHexRGB);
 private:
     Ui::MainWindow *ui;
 
@@ -38,6 +39,7 @@ private:
     char aspect = 'a';
     bool debugMode = false;
     bool fitAspectAxisToWindow = false;
+    QString overlayHexRGB;
 
     Overlay* overlay;