Fix regression in svg output and simplify viewport handling (bug #44765) * gl2ps-renderer.cc (glps-renderer::draw): remove check for GL2PS_NO_FEEDBACK, it it always true after EndViewport * gl2ps-renderer.h (glps-renderer::draw_axes): call gl2psBegin(End)Viewport for every axes and check for GL2PS_NO_FEEDBACK after each axes. * gl2ps-renderer.h (glps-renderer::draw_axes):remove unnecessary "naxes" attribute

function r = __trace__ (t)
  persistent history

  if (isempty (history))
    history = {};
  end
  if (nargin == 0)
    if (nargout == 0)
      history = {};
    else
      r = history;
    end
  elseif (nargin == 1);
    history = [history; t];
  else
    error ('incorrect call to __trace__');
  end

end