is image_viewer obsolete?

[John W. Eaton]

Bug #31161 reports that the image function uses gnuplot even when
another image viewer has been selected with the image_viewer
function.

Is there any reason to keep this feature?  As I stated in my comment
on the bug report, I consider using image viewers other than the
Octave graphics renderer (currently either gnuplot or the new
OpenGL+FLTK backend) to be obsolete because it is highly unlikely that
any external image viewer will ever integrate properly with Octave's
other graphics features.  So rather than fixing the graphics backends
to respect the image_viewer selection, I think we should be removing
support for this feature.

I plan to remove it soon, so if there is any object, please speak up.

Thanks,

jwe