[MLton] compilation problem, doc typos

[Stephen Weeks]

Hi Tom.  Thanks for the bug report.

> I needed to add $(MLTON_ROOT)/basis/unsafe.mlb to
> mlton/mlyacc/src/sources.mlb in order to compile the current CVS
> version with release 20040227. (Otherwise it complains that it can't
> find structure Unsafe.)

This was due to some changes I made this morning (after the release).
mllex no longer generates references to structure Unsafe.  However, to
allow for bootstrapping with old versions of mllex, we still need to
import structure Unsafe.  I did this for MLton proper but not for
mlyacc.  I've checked in the fix you suggested.

> Also I noticed the following typos when reading the documentation
> for the new version:
...

Fixed.