Extend BlockSCAD to allow use of the Customizer Interface

[WillAdams]

I really enjoy BlockSCAD --- it's made me far more productive in OpenSCAD --- Thanks!

But the one feature I use which it doesn't support is the Customizer --- it would be wonderful if one could directly support it in BlockSCAD and that when OpenSCAD code was created it would be compatible with the Customizer (I add comments to help it, but I always have to edit the underlying code).