wxGUI/swipe: remove rendered images after quitting

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@52665 15284696-431f-4ddb-bdfa-cd5b030d7da7

gui/wxpython/swipe/frame.py

@@ -364,6 +364,8 @@ class SwipeMapFrame(DoubleMapFrame):
                    entry = 'wxGUI.MapSwipe')
 
     def OnCloseWindow(self, event):
+        self.GetFirstMap().Clean()
+        self.GetSecondMap().Clean()
         self.Destroy()