[kepler-dev] Checkin supporting relation groups

[Edward A. Lee]

I'm checking in to the Ptolemy tree some core changes to
support "relation groups." You can now create multiple relations
and link them together, which means you have much more control
over the path that connections take.

I've tested the changes in PN, DE, and CT, and have checked in
tests.  Relation groups do not currently work in SDF because
the SDF scheduler is misusing relations. I will work on it next.

The changes required a change to the MoML schema, and I still
need to update the DTD.

A relation group is a maximal set of linked relations. Semantically,
it is identical to a single relation.

Summary of changes:

  ptolemy.kernel.Relation
     Major changes here to support a new abstract syntax.

  ptolemy.kernel.CompositeEntity
     Generate MoML for the new links between relations.

  ptolemy.moml.MoMLParser
     Parse the new MoML for links between relations.

  ptolemy.actor.IOPort
     New protected method _getReceiversLinkedToGroup() that
     supports relation groups.

  ptolemy.actor.IORelation
     Use the new protected method in IOPort, and override _checkRelation()

  ptolemy.vergil.actor.ActorGraphModel and LinkModel
     Support wiring between relations.

Plus various minor changes in other files.



------------
Edward A. Lee
Professor, Chair of the EE Division, Associate Chair of EECS
231 Cory Hall, UC Berkeley, Berkeley, CA 94720
phone: 510-642-0253 or 510-642-0455, fax: 510-642-2845
eal at eecs.Berkeley.EDU, http://ptolemy.eecs.berkeley.edu/~eal