[2.8.0] wxSizerFlag and missing methods

[H]

Hi,

is it possible to add for the next release missing methods for 
wxSizerFlags?

Missing are:

 - All() {return Align(wxALL);}
 - Top() {return Align(wxALIGN_TOP);}
 - Bottom() {return Align(wxALIGN_BOTTOM);}
 - CenterHorizontal() {return (wxALIGN_CENTER_HORIZONTAL);}
 - CenterVertical() {return (wxALIGN_CENTER_VERTICAL);}

If you like you may also implement methods for the other dialect, too.

Hartwig