* works more or less
* updating comment
* removing debugging printf
* adding output
* tweaks
* missed a couple series validations
* testing auto coloring
* updated output.png
* color tests etc.
* sanity check tests.
* should not use unkeyed fields anyway.
The bulk of the code in this package is based on draw2d, but
with significant modifications to make the APIs more golang friendly and careful about units (points vs. pixels).