Make mlyacc emit no trailing whitespace.

Fix for a bug detected by Aditi Barthwal; on Windows the failure to
use $(protect ...) results in passing an unprotected filename to the
command-line, and such filenames may include spaces.

Changed the names of the files in mlyacclib because I want these files
to move into sigobj, and I don't want name-clashes, particularly with
names like stream.sml. (If you use a parser generated by mlyacc, then
you need to have the files in mlyacclib available too.)

Add a MoscowML compilable implementation of MLyacc, using the MLton sources
as the base.