Include a modules connection graph

[kodiweera]

Hi,
I think it's nice to include a modules connection graph of the project which will help new devs to quicikly grasp the flow of the project. I created such a graph for fmriprep using pydeps.

This is a figure and will readily visible if included in the main directory wihout much work. However, whenever a new module is added to the project, a new graph shoud be genrated.

Chandana Kodiweera

[oesteban]

It could be interesting to add this graph to the developer's section of the documentation, and have it regenerate with every documentation build.