Fix problem where mass position channels after the first one not being zoomed

When the code was changed to remove x_list, the code used for zooming was not modified to take it into account.

Closes #201 (closed)

sohstationviewer/view/plotting/plotting_widget/plotting_widget.py

@@ -616,7 +616,7 @@ class PlottingWidget(QtWidgets.QScrollArea):
                     total_points = 0
                     tr_min_ys = []
                     tr_max_ys = []
-                    x, y = ax.x_list, ax.y_list
+                    x, y = ax.x_center, ax.y_center
                     if len(x) == 0:
                         continue
                     if self.min_x > x[-1] or self.max_x < x[0]: