nicehash: use hashrate sold, instead of hashrate produced

[hossbeast]

Nicehash has an api

stats.provider?addr=

which reports the hashing speed as measured by nicehash. It's refreshed every 30 seconds, but its not clear what time period its reporting. I can only guess its the trailing 30 seconds.

autominer currently uses hashing speed as reported locally, by monitoring the miner directly. The speed reported by nicehash is probably more useful. Also, I could compare the two and possibly alert the operator of a misconfiguration that will lead to choosing a suboptimal mining strategy.

[hossbeast]

The data from this API looks like

{
  "profitability": "0.00001367",
  "data": [
    {
      "a": "109.52"
    },
    "0.00212766"
  ],
  "name": "Lyra2REv2",
  "suffix": "MH",
  "algo": 14
}

It's refreshed every 30 seconds, but it seems to be reporting on the trailing 5 minutes, so the data isn't useful until you've been mining that algo for 5 minutes.

(it continues to report a nonzero accepted speed after you stop mining an algo, which continually declines over 5 minutes, and then goes to zero).