openscad quasiquote

I like `circle($fn=6)`, but I don't see it in [the haskell api](https://hackage.haskell.org/package/implicit-0.4.1.0/docs/Graphics-Implicit-Primitives.html#v:circle). While it is possible to encode such optional arguments in haskell, I think a quasiquoter would be better.

```haskell
hex1 d = [scad| circle(d, $fn=6) |] -- too light
hex2 d = [scad2d| circle($$d, $fn=6) |] -- too heavy
hex3 d = [scad| circle($(d), $fn=6) |] -- just right?
```