making some test with svg from illustrator
trying to draw a line with a gradient of several colors. probably close to the solution, but not working yet.
http://www.d3noob.org/2013/01/applying-colour-gradient-to-graph-line.html
http://bl.ocks.org/mbostock/3970883
http://bl.ocks.org/d3noob/3e72cafd95e1834f599b