Zoom on click

[robertocarroll]

When the user clicks on a country, zoom to bounds. See example:

• https://bl.ocks.org/mbostock/9656675
• http://stackoverflow.com/questions/14492284/center-a-map-in-d3-given-a-geojson-object

[robertocarroll]

This was useful: http://techslides.com/demos/d3/d3-world-map-mouse-click-zoom.html

Could do with an active hover colour.