Eggbot 2.0 refrence design.

The files here are:

* Bill of materials, CSV format
* 1/4" plywood pen-arm parts, Inkscape SVG
* 1/4" Poplar pen-arm part, Inkscape SVG
* 0.020" delrin part, Inkscape SVG
* 0.010" acetal copolymer, Inkscape SVG
* Eggbot chassis "acrylic" reference design, Inkscape SVG
* Eggbot chassis original design, geda/PCB
