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 y = bug_59989 ()
  unpacker = @(x) sum (x);
  function y = nest1 (x, a)
    y = a + unpacker (x);
  endfunction
  function y = nest2 (fh)
    x = [2, 3];
    y = fh (x);
  endfunction
  a = 1;
  y = nest2 (@(x) nest1 (x, a));
endfunction