[racket] 80-bit precision in Racket

Matthew,

> I've adjusted the bytecode compiler so that it can deal with more local
> types. To exercise the changes, fixnum results are tracked like flonum
> I plan to clean up the JIT a little bit to make it easier to add extnum

> unboxing, but that's a smaller set of changes. Let me know when you
> start working, and I'll try to not change anything that would make it
> difficult to merge. I imagine that we'll be happy to merge your changes
> into the distribution.

Perfect! I will let you know as soon as we start--pretty soon.

Best regards,

Dmitry