Support GraphicsComplex and NumericArray for SVG generation

[bdlucas1]

Currently the SVG generation routines don't understand how to handle GraphicsComplex and NumericArray used in Graphics* by the new vectorized plotting routines for performance. Implementing this would benefit front-ends that don't want to do their own rendering, and would allow examples to be included in the documentation.

@rocky I think you said at one point you would be interested in doing this?

[rocky]

Currently the SVG generation routines don't understand how to handle GraphicsComplex and NumericArray used in Graphics* by the new vectorized plotting routines for performance. Implementing this would benefit front-ends that don't want to do their own rendering, and would allow examples to be included in the documentation.

@rocky I think you said at one point you would be interested in doing this?

I'm happy to let others do this. Also, I am probably not going to get to this for a while.

My current thought was to use drawsvg2. And do this as an optional Python Module outside of Mathics-core. It gets installed though if one runs pip install -e .[full]

Here are the benefits of doing this:

1. We force a rendering API which is desirable
2. We can remove the SVG rendering from mathics core.
3. We provide support for NumericArray and GraphicsComplex