Yet another Bezier curve implementation

There are many Bezier curve implementations out there, but somehow they all think differently from the way I do. This one thinks the way I do when I create a design:

* I have a sequence of points, and I'd like to connect them with "something curvy".
* So in the first iteration, I specify that sequence of points my curve is supposed to go through, like this:

```
polygon( bezier_curve_seq(
[ [ 0, 0 ], [ 10, 0 ], [ 10, 10 ], ...
))
```
and I render it in OpenSCAD, so I can look at it and it indeed goes through the points I want it to go through.
* Now that I have the basic line correct, I make it curvy, by adding the "handle points" (as a drawing program would show them):
```
polygon( bezier_curve_seq(
[ [ 0, 0 ], [ 10, 0 ], [ 10, 10 ], ...
[ [ [ 3, 3], [ 7, 3 ]], [], ...
))
```
simply by adding a second parameter to my existing invocation, without changing what I have already.
* Between any two points of the seque