including ability to define seriesColors. Appears that charts can have centrally defined object for seriesColors or can use the model to define by chart model instance.
Creating tests for all variations for barChart, but with implementation, since Line chart and Bar chart share CartesianSeries model, must create testing for that as well. Since seriesColor is something that can be defined at higher level, may also have to check all other models (so extra testing).
First implementation of varyColor uses default jqPlot colors, 2nd uses model definition (by chart). Should be able to define by chart, so stackedSeries should be able to have defined color for each chart data series defined.