Rename wxDataViewEvent::SetEditCanceled() and remove its argument

This method should be only used when the edit is really cancelled, so it
doesn't need to take a boolean argument.

It should also use the same spelling as IsEditCancelled() (and for
consistency with the rest of wxWidgets API which uses British English).

Also remove this method from the documentation, it is not part of the
public API.

include/wx/dataview.h

@@ -859,7 +859,6 @@ public:
 
     // for wxEVT_DATAVIEW_ITEM_EDITING_DONE only
     bool IsEditCancelled() const { return m_editCancelled; }
-    void SetEditCanceled(bool editCancelled) { m_editCancelled = editCancelled; }
 
     // for wxEVT_DATAVIEW_COLUMN_HEADER_CLICKED only
     wxDataViewColumn *GetDataViewColumn() const { return m_column; }
@@ -907,6 +906,7 @@ public:
 #endif // WXWIN_COMPATIBILITY_3_0
 
     void SetColumn( int col ) { m_col = col; }
+    void SetEditCancelled() { m_editCancelled = true; }
 
 protected:
     wxDataViewItem      m_item;