hdf5 - > feather

[shimwell]

Looks like feather is smaller, faster etc
https://towardsdatascience.com/the-best-format-to-save-pandas-data-414dca023e0d

[shimwell]

nuclear data load up time is related to docker image size. Currently the docker image is 2.51Gb with just tendl data, adding endf data and it becomes