Loading VSWR marker values failed if only one value was saved.

R+jX charts now have 4 distinct colours for lines as well. (Fixes #39)

NanoVNASaver/Chart.py

@@ -1758,7 +1758,7 @@ class RealImaginaryChart(FrequencyChart):
                 prev_y_re = self.getReYPosition(self.reference[i-1])
                 prev_y_im = self.getImYPosition(self.reference[i-1])
 
-                line_pen.setColor(self.secondaryReferenceColor)
+                line_pen.setColor(self.referenceColor)
                 qp.setPen(line_pen)
                 # Real part first
                 if self.isPlotable(x, y_re) and self.isPlotable(prev_x, prev_y_re):

NanoVNASaver/NanoVNASaver.py

@@ -1186,6 +1186,10 @@ class DisplaySettingsWindow(QtWidgets.QWidget):
 
         self.vswrMarkers: List[float] = self.app.settings.value("VSWRMarkers", [], float)
 
+        if isinstance(self.vswrMarkers, float):
+            # Single values from the .ini become floats rather than lists. Convert them.
+            self.vswrMarkers = [self.vswrMarkers]
+
         self.btn_vswr_picker = QtWidgets.QPushButton("█")
         self.btn_vswr_picker.setFixedWidth(20)
         self.btn_vswr_picker.clicked.connect(lambda: self.setColor("vswr", QtWidgets.QColorDialog.getColor(self.vswrColor, options=QtWidgets.QColorDialog.ShowAlphaChannel)))