am evaluates polynomials.  It first asks for the coefficients
# of a polynomial, which must be entered on one line, highest-order first.
# It then requests values of x and will compute the value of the poly for
# each x.  It will repeatly ask for x values, unless you the user enters
# a blank line.  It that case, it will ask for another polynomial.  If the
# user types quit for either input, the program immediately exits.
#

#
# Function to evaluate a polynomial at x.  The polynomial is given
# as a list of