Maybe simplify the recursive div

[mratsim]

Go just implemented (4 hours ago!) the recursive division by Burnikel and Ziegler.

They avoided the co-recursion between 2n x n and 3n x 2n words and it seems like the implementation is a bit simpler.

• math/big: implement recursive division algorithm golang/go#21960
• golang/go@194ae32

[protolambda]

@mratsim Make sure to copy this critical bugfix if you ever end up implementing the same as Go: golang/go@1e1fa59 (Found by Go ethereum team) (and context: https://twitter.com/peter_szilagyi/status/1332047468004077569)