Region Adjacency Graph

## Example Images
![figure_1](https://cloud.githubusercontent.com/assets/3823490/3291718/5ce9b952-f587-11e3-8c29-e2aace6d7794.png)
![figure_2](https://cloud.githubusercontent.com/assets/3823490/3291723/7074b134-f587-11e3-8c73-d28222891a21.png)


The proper formatting guidelines for docstrings are [here](http://legacy.python.org/dev/peps/pep-0257/) and [here](https://github.com/numpy/numpy/blob/master/doc/HOWTO_DOCUMENT.rst.txt). You've mostly got these right but it's good to check them every now and then. =)