==== Mirror ====

Shapes can mirror (reflect) about the X, Y, or Z axis, and more specifically about any ''origin''.

//[[http://www.mathsisfun.com/geometry/reflection.html|Learn about reflection at MathIsFun.com]]//

Defaults:
  * origin : [0, 0, 0]
  * normal : [0, 0, 1] (mirror about the Z axis)

<code javascript>
const myshape = cube({size: [5, 20, 5]})
const newshape = mirror({origin: 3, 3, 3], normal: [1, 0, 1]}, myshape)
</code>

There are simple versions of this function to mirror a single axis about the origin.

<code javascript>
const myshape = cube({size: [5, 20, 5]})
let newshape = mirrorX(myshape)
newshape = mirrorY(newshape)
newshape = mirrorZ(newshape)
</code>