add a hive plot type

[cjyetman]

add a hive plot type, as described here: https://bost.ocks.org/mike/hive/

There's an open PR #110 from over a year ago that adds a hive plot type. At a minimum it would need to be rebased, and probably carefully reviewed. Otherwise it could be recreated from scratch.

[timelyportfolio]

Very rough https://github.com/timelyportfolio/d3hiver with post http://www.buildingwidgets.com/blog/2015/7/11/week-27-d3hiver in d3v3.