Work around decorated_image's lack of properties, for the recorder.
* apps/morphers/recorder.hh (trait::image_< decorated_image<I,D> >): Replace with.. (trait::image_< decorated_image<I, recorder<I> > >): ...this. Add a value_storage property. (ch_value_< decorated_image< image_<I>, data_< recorder<I> > >, V >): New trait, to handle changes of value types in images decorated with a recorder. * apps/morphers/mask+channel.cc, * apps/morphers/mask+recorder.cc, * apps/morphers/recorder.cc: Simplify these programs thanks to the preceding changes.