Correct typo in |> entry; get it to sort correctly in REFERENCE.

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!

Start working on porting the doc building system to SML (i.e., not Moscow ML)
to get it working with Poly ML.