Remove TABs from source files (and some trailing w/space)

extra semicolons removed from (some) .sig files

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!

Initial version of theory and libraries of rational numbers added.