Although the clock won't run out for two more weeks, I'm putting SRFI 124
into last call. I've fixed the bugs in the Racket implementation (I hope),
added more references from the mailing list, cleaned up the implementation
sections. I have *not* added Riastradh's proposed fence instruction,
since it is not found in any existing version of ephemerons. If someone
wants to argue the case, go for it.
Arthur, please push <http://www.ccil.org/~cowan/temp/srfi-124.html> to
the repo. Thanks.