Removed trailing whitespace from all .sml and .sig files.

This affects over 900 files and was done using emacs's delete-trailing-whitespace
function in batch mode. Building the system with Poly/ML and Moscow ML seems to
work, so I'm hoping these changes don't break anything. Please complain if
they do!

Revisions, mainly to add machine words and their operations to the
source language.

Revised build so that system can be separately compiled. Also moved
test programs to separate directory.

A blank new implementation of the software compiler