[Sml-implementers] flexible records

[Stephen Weeks]

> Cool!  Some of those cases in flexrecord.sml are pretty pathological.

Yeah, each one of them found a new bug.  Andreas comes up with good
examples.

But please, make up some more tests and add them to flexrecord.sml.
One thing that hasn't been tested is multiple flexrecords being
generalized in the same scheme, even worse, with multiple unknown
components each.

Now, on to Ssa.Function.checkHandlers, but first I've gotta proofread
a paper, and I'm on vacation for the weekend, so expect no results
until Monday.