WIP Update to remove Enum_Context and clean up tests to match new pro…

…posal

This push removes the Enum_context and returns 3 arguments from an open
or pull (instances, end_of_sequence, enum_context

The enum_context  is a tuple that contains the serer enum_ctxt and the
namespace.

This also cleans up most of the documentation.  Note that there are a
couple of issues around MaxObjectCount to be worked out.

This is only a WIP