Removed excess logging
Fixed zooming in node link diagrams
New improved color specification for scatter plots

- Assumes data has either a labels field (with group assignments) or a
color field (with rgb values)
- A new function will parse these into lists of d3 rgb objects, and
then zip them with the data. Keeping data bound to colors makes updates
/ appends much easier.
- Drawing routines can use these rgb objects, if they exist, otherwise
use defaults (which are specified in the plot type rather than in css).