new snapshot

[Matthew Fluet]

> I just put a new snapshot at http://www.star-lab.com/sweeks/src.tgz

Good timing.  I just squashed last known bug in my current version of the
x86 backend.  I only need to add in the profiling labels.  After our
discussion last week, I think that the easiest thing to do will be to wrap
each assembly block in labels like

MLtonProfileBegin_ChunkName_BlockProfileName_BlockLabel
MLtonProfileEnd_ChunkName_BlockProfileName_BlockLabel

Those should correspond to the three granularities of profiling.

> Matthew, here are some of the changes I made to your files

Those all look reasonable.  I'll also investigate the right types of
property lists.  One question, if I don't make a property destructable,
will it just last until the end of the compilation?  I tended to make
properties destructable if I knew when I was going to be done with it.
Maybe that's not necessarily the most efficient?