Add kitty graphics protocol support

[wookayin]

Work in progress. Upstream issue: #4

https://sw.kovidgoyal.net/kitty/graphics-protocol.html

• [x] works on plain kitty terminal e.g. python -m imgcat FILENAME.png or imgcat(np.array(...))

• [ ] tmux support: it can print graphics, but they do not get cleared well

  • pixels per line information is missing, so it is quite difficult to allocate proper amount of spaces

• [ ] Support all parameters

/cc @teto

[ElPiloto]

Any chance this will get merged?

[wookayin]

I'll finish this soon. Thanks for bumping up!

[kzhang2]

Bumping this PR! I would also find this very useful.

[newzealandpaul]

Would be great to have this merged

[wookayin]

I can merge this soon, but it's really annoying (currently impossible) to make imgcat work well inside tmux. This is the limitation of kitty.