Overhaul image, imagesc to use newplot and support low-level invocation form. * scripts/image/image.m: New variable do_new indicates high-level calling form. For high-level invocation, call newplot before __img__. Correct linearity check if vectors are reversed (high-to-low values). Only apply image properties to axes if doing a high-level invocation. * scripts/image/imagesc.m: New variable do_new indicates high-level calling form. Delete subfunction __imagesc__ and incorporate minimal amount of code into imagesc. Only apply climits for high-level invocation.

## The `oregonator'.
##
## Reference:
##
##   Oscillations in chemical systems.  IV.  Limit cycle behavior in a
##   model of a real chemical reaction. Richard J. Field and Richard
##   M. Noyes, The Journal of Chemical Physics, Volume 60 Number 5,
##   March 1974.

function dx = oregonator (x, t)

  dx = zeros (3, 1);

  dx(1) = 77.27*(x(2) - x(1)*x(2) + x(1) - 8.375e-06*x(1)^2);
  dx(2) = (x(3) - x(1)*x(2) - x(2)) / 77.27;
  dx(3) = 0.161*(x(1) - x(3));

end