octree

``
var Octant = require('./octree');

var modelWidth = 4
var modelHalfWidth = modelWidth / 2;
var modelBounds = [
[-modelHalfWidth, -modelHalfWidth, -modelHalfWidth],
[modelHalfWidth, modelHalfWidth, modelHalfWidth]
];
var root = new Octant(modelBounds);
root.insert([1.0, 1.0, 1.0], 1);
`

the resulting octree in root looks like this:

`
{
children: [{
children: [, , , , , , , ],
aabb: [
[-2, -2, -2],
[0, 0, 0]
],
isLeaf: true,
solid: false,
width: 2
}, {
children: [, , , , , , , ],
aabb: [
[0, -2, -2],
[2, 0, 0]
],
isLeaf: true,
solid: false,
width: 2
}, {
children: [, , , , , , , ],
aabb: [
[0, 0, -2],
[2, 2, 0]
],
isLeaf: true,
solid: false,
width: 2
}, {
children: [, , , , , , , ],
aabb: [
[-2, 0, -2],
[0, 2, 0]
],
isLeaf: true,
solid: false,
width: 2
}, {
children: [, , , , , , , ],
aabb: [
[-2, -2, 0],
[0, 0, 2]
],
isLeaf: true,
solid: false,
width: 2
}, {
children: [, , , , , , , ],
aabb: [
[0, -2, 0],
[2, 0, 2]
],
isLeaf: true,
solid: false,
width: 2
}, {
children: [{
children: [, , , , , , , ],
aabb: [
[0, 0, 0],
[1, 1, 1]
],
isLeaf: true,
solid: true,
width: 1
}, {
children: [, , , , , , , ],
aabb: [
[1, 0, 0],
[2, 1, 1]
],
isLeaf: true,
solid: true,
width: 1
}, {
children: [, , , , , , , ],
aabb: [
[1, 1, 0],
[2, 2, 1]
],
isLeaf: true,
solid: true,
width: 1
}, {
children: [, , , , , , , ],
aabb: [
[0, 1, 0],
[1, 2, 1]
],
isLeaf: true,
solid: true,
width: 1
}, {
children: [, , , , , , , ],
aabb: [
[0, 0, 1],
[1, 1, 2]
],
isLeaf: true,
solid: true,
width: 1
}, {
children: [, , , , , , , ],
aabb: [
[1, 0, 1],
[2, 1, 2]
],
isLeaf: true,
solid: true,
width: 1
}, {
children: [, , , , , , , ],
aabb: [
[1, 1, 1],
[2, 2, 2]
],
isLeaf: true,
solid: true,
width: 1
}, {
children: [, , , , , , , ],
aabb: [
[0, 1, 1],
[1, 2, 2]
],
isLeaf: true,
solid: true,
width: 1
}],
aabb: [
[0, 0, 0],
[2, 2, 2]
],
isLeaf: false,
solid: false,
width: 2
}, {
children: [, , , , , , , ],
aabb: [
[-2, 0, 0],
[0, 2, 2]
],
isLeaf: true,
solid: false,
width: 2
}],
aabb: [
[-2, -2, -2],
[2, 2, 2]
],
isLeaf: false,
solid: false,
width: 4
}
``