Our form of representing polynomials using the *index* for the exponent is
not so good for a polynomial like
\(4 x^{512} + 7 x^{256} + 1\)
We could also represent polynomials by a list of lists. e.g.
.. sourcecode:: python

[[4,512],[7,256],[1,0]]

Here each term is a two element list of `[coefficient, exponent]`

Rewrite polynomials.py so that it uses this new representation of a polynomial.

`modified: Thu Jan 28 11:25:57 PST 2016`