[Gtk-sharp-list] SymbolTable refactor

[Mike Kestner]

I committed a rather large refactoring of the generator SymbolTable
tonight.  I've been wanting to get a handle on it for a while, since it
had grown to be almost as much of a mess as the Parameters class.  I
gutted a lot of redundant code, but I'm not done yet. I want the
generation to look up IGeneratables from the table and use them directly
to produce code, instead of using the SymTab as a go between the way it
is now.

The generation statistics produced before and after the patch are
identical, and I've run my usual test suite from the sample dir without
incident.  Let me know if any of the bigger apps end up tripping on
anything I might have missed.

I mainly did this work because I needed to add something to the
SymbolTable for the last set of helper class internalizations. I'll be
working on that next.  To my knowledge, the only exposed helper classes
left are the callback helpers.  If the docs folks are aware of anything
else that they don't think should be exposed, let me know.

-- 
Mike Kestner <mkestner@speakeasy.net>