fix benchmark, bump rrdir, add rrdir.stream

[silverwind]

async rrdir shouldn't look so bad anymore with this

[thecodrr]

@silverwind hey, thanks for the PR. I will update the benchmaks. I had to downgrade rrdir very drastically (to 2.0.0) as it doesn't support Node < 10 after that.

I will post new benchmarks for Node 8.x seperately.

Thanks again.

[silverwind]

Okay. I pushed 6.1.2 in the meanwhile which should give another small speed boost. Feel free to update yourself. I don't support Node 8 anymore because it's end-of-life.

[thecodrr]

Okay cool. I will update the benchmark.