Extend Redblackmap with update and findKey operations

update allows you to set the value for a key to some function of its old
value without traversing the tree twice. findKey returns the inserted
key along with its value, which may be useful if the lookup key is
different but still EQUAL as a key.

Strictly speaking these are not extensions to the original code, since I
have taken the obvious code reuse opportunities. So now find and insert
might waste some cycles constructing and deconstructing options and
closures.

Function fromList added.

Added a function insertList.

Added a function isEmpty that returns true if its argument is the empty map,
and false otherwise.

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!

Updated to the latest version of Ken's private copy

Red-black implmentations of the Binarymap signature. Quite possibly
very buggy. Didn't seem to make a big efficiency difference in Term.compare so
I didn't test them extensively.