[Grace-core] Dialect encoding

[James Noble]

> As I understand it, an unqualified method call results in the following lookup:

This seems right to me, although there is no priority of inheritance over nesting;
a method found in both is ambiguous and thus an error.

I think we also (nominally) look both for nesting & inheritance in super-objects -
rather than e,g, just doing inheritance up the super chain, and just nested up the 
lexical chain.   I don't think minigrace has this right, however.

This means e.g. that nesting variables in an anonymous outer scope can't give 
us "private" behavior - whereas if inheritance only looked up the super chain
it could.

Gilad has a paper in the DYLA workshop going into this in detail.

James