Amended WITH-VALUES and VALUES.

[Guillermo J. Rozas <jinx@hpesogg.hp.com>]

    As Jqnathan Rees points out, the proposal should explicitly say
    something about what the arity of implicit continuations.  My
    compromise proposal says nothing about that subject because I thought
    it would eliminate the chance of reaching an agreement.  I have an
    opinion on the subject, but I will not propose it in the interest of
    getting multiple values into Scheme.  Implementations may explore many
    alteratives.  With the current proposal, implementation may or may not
    ignore extra values returned by a procedure.  All it requires is that
    the number of arguments generated by the first argument of WITH-VALUES
    matches the arity of the second argument of WITH-VALUES, and (values
    E) returns E.  To make the situation about VALUES clear, I added a note
    to that section.

I will accept the proposal if it leaves the arity of implicit
continuations unspecified, and it is explicitely stated.