#### [ArrayList or Array].matrix3d

Creates a 3D matrix.

```javascript
let matrix3d = ArrayList.matrix3d(3,"a");
// it will result in a 3x3 matrix with the value "a" on every element
[
  [ [ 'a', 'a', 'a' ], [ 'a', 'a', 'a' ], [ 'a', 'a', 'a' ] ],
  [ [ 'a', 'a', 'a' ], [ 'a', 'a', 'a' ], [ 'a', 'a', 'a' ] ],
  [ [ 'a', 'a', 'a' ], [ 'a', 'a', 'a' ], [ 'a', 'a', 'a' ] ]
]
```
