Not choosing random node if multiple nodes have same distance

[TheColorman]

I originally posted this issue to knn, but I realised that the issue was due to a limitation here (#19).

If there are 2 nearest nodes with the exact same distance to the test node, the returned node will always be the last one.
Example:

var points = [
    { x: 1, y: 2, label: 'A' },
    { x: 3, y: 4, label: 'B' },
    { x: 5, y: 6, label: 'C' },
    { x: 5, y: 6, label: 'E' },
    { x: 7, y: 8, label: 'D' },
];

var distance = function (a, b) {
    return Math.pow(a.x - b.x, 2) + Math.pow(a.y - b.y, 2);
}

var tree = new kdTree(points, distance, ["x", "y"]);

var nearest = tree.nearest({ x: 5, y: 5 }, 1);

console.log(nearest);
// > [ [ { x: 5, y: 6, label: 'E' }, 1 ] ]

Both node E and node C have the same distance from the test node (distance=1), yet node E is always returned no matter what.

Expected behaviour:
If multiple nodes could be chosen as the nearest node and maxNodes is set to 1, the returned node should be chosen at random.