+ *) Change the array representation of binary polynomials: the list
+ of degrees of non-zero coefficients is now terminated with -1.
+ Previously it was terminated with 0, which was also part of the
+ value; thus, the array representation was not applicable to
+ polynomials where t^0 has coefficient zero. This change makes
+ the array representation useful in a more general context.
+ [Douglas Stebila]
+