Call map

Create a map of function calls:
```
conda install pydot
pip install git+https://github.com/ttylec/pyan
cd sciunit
# Make a GraphViz dot file containing a static function call map of the project
pyan *.py --dot --colored --no-defines --grouped > map.dot
# Turn it into a .png file
dot -Tpng map.dot > map.png
```