PR proposal: per-row diff for screen updates?

Hiya! Great library!

I wrote an IRC client with FTXUI. It works fine locally but when I use it over high-latency links, I really feel how each character I type does a whole screen refresh. It's pretty unusable that way.

I made a simple patch to FTXUI to only send rows that changed instead of the whole screen and it's a lot more usable now.

Assuming I am not doing something dumb or missing something obvious, would this patch be welcome? I can polish it up into a proper PR if so.

Thanks!