code style: space after parenthesis in "(x*y)list"

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!

A load of changes aimed at supporting records better. And some other
odds and ends.

Preliminary addition of support for ML execution.