* Add extension nbsphinx-link: link notebook out of the sphinx root folder to the sphinx project
* Link Notebook custom.ipynb directly from python folder to the sphinx project
* Link Notebook seq_and_func.ipynb directly from python folder to the sphinx project
* Small title fix
* Make interactive graphs visible in readthedocs webpage for seq_and_func.ipynb
* Regenerate outputs for custom.ipynb and remove parts of them
