Add JSON output for CSG objects

[sethrj]

CHAINED on #1130.

Example:

{
  "_type": "all",
  "daughters": [
    {
      "_type": "shape",
      "interior": {
        "_type": "cone",
        "halfheight": 2.0,
        "radii": [
          1.0,
          0.5
        ]
      },
      "label": "cone"
    },
    {
      "_type": "transformed",
      "daughter": {
        "_type": "shape",
        "interior": {
          "_type": "cylinder",
          "halfheight": 2.0,
          "radius": 1.0
        },
        "label": "cyl"
      },
      "transform": {
        "_type": "transformation",
        "data": [
          1.0,
          0.0,
          0.0,
          0.0,
          0.7071067811865475,
          -0.7071067811865475,
          0.0,
          0.7071067811865475,
          0.7071067811865475,
          1.0,
          2.0,
          3.0
        ]
      }
    },
    {
      "_type": "shape",
      "interior": {
        "_type": "ellipsoid",
        "radii": [
          1.0,
          2.0,
          3.0
        ]
      },
      "label": "ell"
    },
    {
      "_type": "transformed",
      "daughter": {
        "_type": "shape",
        "interior": {
          "_type": "sphere",
          "radius": 1.25
        },
        "label": "sph"
      },
      "transform": {
        "_type": "translation",
        "data": [
          1.0,
          2.0,
          3.0
        ]
      }
    }
  ],
  "label": "all_quadric"
}

[sethrj]

@elliottbiondo this one next please!