[MLton] cvs commit: improved analysis for ref flattening

[Matthew Fluet]

>   Feel free to try out the new analysis (via -diag-pass refFlatten) on
>   your code and see what happens.

refFlatten seems to have gotten a bunch of stuff in the CML library.
Nothing jumped out at me as being obvious as to what was being flattened;
CML uses a lot of refs in different places; I'd hope that the imperative
queues (represented as two list refs) got flattened.

CML ends up with some really huge environments, with a bunch of refs being
flattened into them.  It should be an interesting case to come back to
with safe-for-space in mind.