mlprof output

[Matthew Fluet]

> Matthew, let me know if you want to work on any other of the todo stuff before
> the next release.  I'm completely swamped here with InterTrust work and won't
> have a lot of time over the next couple weeks.  As a reminder here's what needs
> doing: MLton.size bug, Time bug, benchmarking, docs.

I'll try to look at the Time bug over the weekend, since I seem to be the
only one who is affected by it.  What is the MLton.size bug?  If it's not
too difficult, I'll try and get that one too, as I'll probably be
modifying the runtime anyways.