Boolean operation

Boolean geometry operations require the geometry it operates on to be defined:

Property	Type	Description
`type`	`'union', 'intersection', 'difference', 'xor'`
`condition`	`formula` (optional)
`repeat`	repeat (optional)
`step`	`boolean, formula` (optional)
`defs`	Definition (optional)
`geometry`	Geometry	The geometry used in the Boolean operation

{
  type: "union",
  geometry: [
    { type: "ellipse",
      x: 0.25,
      w: 0.75,
      h: 0.75
    }
    { type: "ellipse",
      y: 0.25,
      w: 0.75,
      h: 0.75
    }
  ]
}

{
  type: "intersection",
  geometry: [
    { type: "ellipse",
      x: 0.25,
      w: 0.75,
      h: 0.75
    }
    { type: "ellipse",
      y: 0.25,
      w: 0.75,
      h: 0.75
    }
  ]
}

{
  type: "difference",
  geometry: [
    { type: "ellipse",
      x: 0.25,
      w: 0.75,
      h: 0.75
    }
    { type: "ellipse",
      y: 0.25,
      w: 0.75,
      h: 0.75
    }
  ]
}

{
  type: "xor",
  geometry: [
    { type: "ellipse",
      x: 0.25,
      w: 0.75,
      h: 0.75
    }
    { type: "ellipse",
      y: 0.25,
      w: 0.75,
      h: 0.75
    }
  ]
}