Add DoHideCellEditControl() for symmetry

This also allows to reset m_cellEditCtrlEnabled earlier, as we don't
have to keep it true for the duration of HideCellEditControl()
execution.

No real changes, as with the previous commit, this one is best viewed
ignoring whitespace changes.

include/wx/generic/grid.h

@@ -2908,11 +2908,12 @@ private:
                 );
     }
 
-    // Show the cell editor for the current cell unconditionally.
+    // Show/hide the cell editor for the current cell unconditionally.
     void DoShowCellEditControl();
+    void DoHideCellEditControl();
 
     // Accept the changes in the edit control, i.e. save them to the table and
-    // dismiss the editor.
+    // dismiss the editor. Also reset m_cellEditCtrlEnabled.
     void DoAcceptCellEditControl();
 
     // As above, but do nothing if the control is not currently shown.