add: config.scale option

[netpyoung]

It will be good to support config.scale option for small size radar.
It produces 700/500 size radar from 1400/1000.

radar_visualization({
  svg_id: "radar",
  width: 1400,
  height: 1000,
  scale: 0.5,   ;; <<----

[bocytko]

Thanks for the PR!

The two screenshots below showcase the value of scaling (here: with scale 1.5).
If just the width/height is increased, the radar is just shifted to the center leaving a lot of whitespace:

The scale attribute scales the radar SVG to occupy the full dimensions: