RegistryDM

This currently contains Registry and VOSI data models which have been transformed from their XML schema representation (mostly automatically). It is an experiment to see if any lessons may be learnt from the extra rigour that VO-DML imposes. The collection of models has been given the version number 1.5 to indicate that they might be the transition between the VOResource 1.0 series and a possible 2.0 set of models.