Add json option.

[seagreen]

No description provided.

[seagreen]

First question: how do you feel about the structure of the output?

Example output for the command chronos 'sleep 0.1' 'sleep 0.2' --timeout 0.5 --json:

{"sleep 0.2":{"mean":{"denominator":2000000000,"numerator":407070367},"squared-weights":2,"samples":2,"q-factor":{"denominator":2000000000000000000,"numerator":2931247881}},"sleep 0.1":{"mean":{"denominator":2000000000,"numerator":207569483},"squared-weights":2,"samples":2,"q-factor":{"denominator":2000000000000000000,"numerator":34338684249}}}

Or, prettified:

{
  "sleep 0.2": {
    "mean": {
      "denominator": 2000000000,
      "numerator": 407070367
    },
    "squared-weights": 2,
    "samples": 2,
    "q-factor": {
      "denominator": 2e+18,
      "numerator": 2931247881
    }
  },
  "sleep 0.1": {
    "mean": {
      "denominator": 2000000000,
      "numerator": 207569483
    },
    "squared-weights": 2,
    "samples": 2,
    "q-factor": {
      "denominator": 2e+18,
      "numerator": 34338684249
    }
  }
}

One thing that might be improved is the encoding of rationals.

[knupfer]

I think that's quite good. One thing to think of is that this wouldn't allow for consumption of intermediate results, so we could instead print out a lazy list of objects and if the user likes to get only one output he has to combine it with print-once.

[seagreen]

I like that idea. I think it will make the code a little nicer too. I'll update the PR when I get a chance.

[seagreen]

Got busy and am going to abandon this, hopefully someone else can pick it up.