_changeProperties on a Publishable doesn't set HasUnpublishedChanges

Summary: That is, if you use _changeProperties() on a Publishable, the changes will land on the Publication fork. But it doesn't light up the Publish button.

The problem here is that HasUnpublishedChanges currently gets set in EditFunctionsImpl.doChangeProps(). That can't be right, since there are a number of other ways that you can change something.

Test whether the same problem is true iff you use _createThing() to create a Publishable -- I would bet that it is. (Figure out where the relevant set code currently is.)

The right place to fix this is probably in SpaceCore.receiveCommand(), modifying the props before we do the rest of the processing. But be careful with this -- that code is delicate enough as it is.