code: function getIntersectionPoints(circles) {
          var ret = [];
          for (var i = 0; i < circles.length; ++i) {
              for (var j = i + 1; j < circles.length; ++j) {
                  var intersect = circleCircleIntersection(circles[i],
                                                                circles[j]);
                  for (var k = 0; k < intersect.length; ++k) {
                      var p = intersect[k];
                      p.parentIndex = [i,j];
                      ret.push(p);
                  }
              }
          }
          return ret;
      }
docs: Gets all intersection points between a bunch of circles