Drive-by: make final convenience methods that defer to another method.
Checkpoint on config flattener.
Honor the output directory parameter.
Added note about stable hashing.

The other problem I need to solve is dependency ordering.
Let's say A uses B, and B uses C.
If I rewrite B's use of C prior to rewriting A, then parameters
get filled back in on B.

It's complicated by the fact that dependencies cross group boundaries.

There's a DependencyGraph class in samskivert, I'll look into that tomorrow...