Because this function produces a string value it would more intuitive to
just to return this string as a function value instead of passing it
through the parameter.
Current wxPG_FILE_DIALOG_TITLE and wxPG_DIR_DIALOG_MESSAGE attributes can be used to customize editor dialog titles only for wxFileProperty and wxDirProperty, respectively. New wxPG_DIALOG_TITLE property is applicable to all properties derived from wxEditorDialogProperty so not only editor dialog titles for wxFileProperty and wxDirProperty can be set but also for wxFontProperty, wxLongStringProperty, etc.
wxPG_FILE_DIALOG_TITLE and wxPG_DIR_DIALOG_MESSAGE attributes are marked obsolete.
wxFontProperty and wxMultiChoiceProperty use TextCtrlAndButton editor so they can be implemented as parents of wxEditorDialogProperty to share common functions and data.
So far it was implemented as property which could take int values 0/1 so it was acting essentially as a Boolean property. Implementing it explicitly as a Boolean one will make it more intuitive. Legacy code setting 0/1 int values shouldn't be affected because conversion from int to bool is implicit.
