save overlap edit settings when reopening

Author: kkiesling

openmc_plotter/main_window.py

@@ -414,6 +414,7 @@ def updateEditMenu(self):
         self.maskingAction.setChecked(self.model.currentView.masking)
         self.highlightingAct.setChecked(self.model.currentView.highlighting)
         self.outlineAct.setChecked(self.model.currentView.outlines)
+        self.overlapAct.setChecked(self.model.currentView.color_overlaps)
 
         num_previous_views = len(self.model.previousViews)
         self.undoAction.setText('&Undo ({})'.format(num_previous_views))