You can view html rendered versions of the Jupyter notebooks that describe the proposed changes at http://www.clawpack.org/new_features_for_v5.7.0/notebooks_html/Index.html.
To execute the notebooks, clone the repository and open
notebooks/Index.ipynb.
The other directories contain the new code, which will be added to various clawpack repositories via a sequence of PRs separating out some of the distinct changes.