WIP: [sphinx] For some reason the matplotlib intersphinx reference for pyplot changed…

Follow a proper solution @mguenther. For some reason the matplotlib intersphinx reference for pyplot changed the name (the reference as :py:mod is not available in the inventory anymore). As mentioned in the commit, we would need a new release of this package if we want to have a green stable nightlies.

I also prepared a script that makes easier the task of finding the correct inter-sphinx links bob.admin!64 (merged)

Thanks

Closes #29 (closed)