Using a named format string in code gen of endpoint/service constructors.
Minor changes: made a few endpoint variables final.
When initially construct an endpoint/service, logging its internal, global variables.  This way, know which ralph objects are mapped to endpoint variables.
Added code so that endpoint constructor object takes a list of
arguments it can use to set internal data of an endpoint.  This is for
rebuilding endpoints/services from version log.  Still need to
actually test changes.
Updated emit tests so that they implement the new EndpointConstructorObj interface.