Python 3, remove some bundled code
Async Pong support

The idea is to cause CursorHold from another thread.

There are two implementations:
 - GTK - listen on a file descriptor
 - TTY - inject FEFF in the tty and map it to CursorHold (requires patched vim)
More cleaning up.
Clean and fix diagnostics.

Probably still very broken
Remove some more broken tests

The only test is vim. Everything is broken.