add SIXEL support for terminal display

[fchapoton]

see https://groups.google.com/d/msg/sage-devel/rJ_W0EgRLMg/5B5UU2VyAAAJ

for a discussion of this.

Python interface there: https://github.com/saitoha/PySixel

and

https://github.com/saitoha/libsixel

See also: https://github.com/koppa/matplotlib-sixel

CC: @embray @slel

Component: interfaces

Issue created by migration from https://trac.sagemath.org/ticket/26544

[mkoeppe]

comment:3

The macOS terminal does not seem to support this, nor does iTerm2; but for the latter there's #21040.

[fchapoton]

comment:5

now there is Euporie

https://euporie.readthedocs.io/en/latest/

[fchapoton]

So I think we can close this, and let people try to use Euporie with a sagemath kernel if they want.

[mkoeppe]

Nice find.