D3v4 plugin example fail on pretest with rollup builder version 0.44 or newer

[Juan Pablo Kutianski]

Mike

I made a plugin based on https://bost.ocks.org/mike/d3-plugin/d3-plugin.zip and works fine with rollup builder up to version 0.43 of this module.

The newer versions change the object extend behaviour and overwrite the global d3 object with {}

extend

Boolean whether or not to extend the global variable defined by the moduleName option in umd or iifeformats. When true, the global variable will be defined as (global.moduleName = global.moduleName || {}). When false, the global defined by moduleName will be overwritten like (global.moduleName = {}).

You can see the change I made to use the newer versions on my plugin d3.templating. 

Best.

Juan Pablo