Appears to work - need some real test data

I crudely tested convergence of smoothing of the sine primitive, for
different values of dx, by comparing the different smoothened values
with the value of sin x. Doesn't feel like a good test though.
I iz the NEO nao!

I don't even want to _begin_ paper interpretation of the nth-root
procedure. It works - but how the magic is it doing that?!
General-purpose iterative improvement

square-root works :)

The iterative-improve procedure did not converge for the longest time
because I carelessly omitted the tolerance value (0.0001) in the lambda
procedure passed as the good-enough? argument inside the square-root
procedure.
Typed out and tested chapter examples
Construct a better rational number representation

Piece of cake! (Which means there's a really steep slope coming up
pretty soon! :D)
Fixed file name to comply with my convention