Support multiple arguments

[paul-english]

Multiple arguments aren't currently supported, e.g. functions like

(fn [x] (- (- (exp x) 1.5)
                     (atan x)))

would be much more idiomatic if it could be written,

(fn [x] (- (exp x) 1.5 (atan x)))

This should work with lift-real-n->real and lift-real-n+1->real but with earlier testing there seemed to be an error here.