Starry night using ipythonblocks

This is my lesson for SWC instructor training. It builds on [Matt's][1] [starry night example][2] but uses nested for loops instead of zip, and adds in a routine to reduce the color palette. The intended audience are novice users who have been introduced to ipythonblocks, and hopefully reinforces concepts like nested loops and the oddities of integer division in Python 2.x. Feedback appreciated.

[1]: https://github.com/jiffyclub
[2]: http://nbviewer.ipython.org/github/jiffyclub/ipythonblocks/blob/master/demos/starry_night_to_text.ipynb