[Grace-core] Encoding classes

[James Noble]

Argh. I meant to add: 

Good news: we can I think keep the class syntactic form even if we change the encoding. 

Good news: we can still use the encoding as a simple example of how classes work. 

I don't think this affects Grace programmers much either way. I think the most important things are if classes (factories) are objects, "new" is a method request, how generics work, and how / if classes subtend types.

J