wxGUI: uninitialize aui manager when destroying map display to fix https://trac.osgeo.org/grass/ticket/3237

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@70296 15284696-431f-4ddb-bdfa-cd5b030d7da7

gui/wxpython/mapdisp/frame.py

@@ -855,6 +855,7 @@ class MapFrame(SingleMapFrame):
             if pgnum > -1:
                 self.layerbook.RemovePage(pgnum)
         Debug.msg(2, "MapFrame.OnCloseWindow(): function ends")
+        self._mgr.UnInit()
         self.Destroy()
 
     def Query(self, x, y):