delaunayn: adjust node ordering for positive outward normal vectors (bug #53397) * delaunayn.m: Check sign of simplex volume, flip node order for negative volumes to ensure positive (outward-pointing) normal vectors. Add BISTs to check for positive volumes. * etc/News.8.md: Append function improvement note to delaunayn change paragraph under General Improvements.

function fh = nested_test_3 ()
  a = 3;
  b = 5;
  c = 7;
  f1 = @(f, x) f(x) + a;
  fh = @(y) f1 (@(z) z^2 + b*y, y) + c;
endfunction