[Grace-core] Information hiding

[Kim Bruce]

To make the use of libraries effective, we will need a way of restricting information to within a module.  I am seeing lots of examples where I need the equivalent of Java's package scope.  A couple of classes need to reference the confidential portions of each other, but we don't want to make these methods public.  "Confidential" works fine for inheritance, but we need something more.

No need for immediate action, but we need to talk about "annotations" in general sometime soon.  Perhaps I can come up with a proposal based on my experience writing Grace libraries.

Kim