A super hacky attempt at using $kak_command_fifo instead of a socket connection

[Screwtapello]

This was my exploration for #14.

In practice it's a lot choppier than the original implementation, but using $kak_response_fifo to keep things in lockstep means scrolling still completes in the same (wall clock) time, just at a lower frame rate.

[caksoylar]

Thanks, this looks like it simplifies a lot of code! Let me know if you have further comments on the long term experience; I will start using it as well to see how it performs.