[Pie] - Pie plot v1

Pie plots are coming into demand and we should implement it.  This should implement a v1 of the pieplot, giving relevant project calls, a default color scale, and some important primary projector attributes.
Placing a comment in to explain, but I'll tldr here.  The data to bind into the selection is not the dataset but a transformed version after it goes through the d3 pie layout function.

https://github.com/mbostock/d3/wiki/Pie-Layout

What's nice is that this does not affect the underlying data, but it does mean we need to do a bit of rerouting so the projectors point where they expect to point.