experimenting with the SVG attributes viewBox and preserveAspectRatio
created with d3js v4 and ES2015
forked from enjalot's block: viewBox space coordinate transformation
forked from micahstubbs's block: viewBox space coordinate transformation
https://cdnjs.cloudflare.com/ajax/libs/d3/4.1.1/d3.min.js
https://npmcdn.com/babel-core@5.8.34/browser.min.js