Implements the hammer edge bundling by Ian Calvert.
Details
This function only wraps existing python code from the datashader library. Original code can be found at https://gitlab.com/ianjcalvert/edgehammer. Datashader is a huge library with a lot of dependencies, so think twice if you want to install it just for edge bundling. Check https://datashader.org/user_guide/Networks.html for help concerning parameters bw and decay. To install all dependencies, use install_bundle_py.
see online for plotting tips