New pattern: tessellation

The code for this one is kinda insane, but it seems to be working. To be ultra-geeky about it, this is a 3.4.6.4 semi-regular [tessellation pattern](http://en.wikipedia.org/wiki/Tessellation). The size of the individual pieces is dynamic and then each has variable color and opacity like the other patterns.

![screen shot 2014-02-06 at 1 23 19 pm](https://f.cloud.github.com/assets/6104/2102283/bfbaa424-8f5c-11e3-8f3f-79a7c67f4560.png)