Make the vignette run "out of the box":

• Update documentation
• Update and use the repo-tracked NIS data
  • Add data/get_nis.py
  • Remove old NIS data in data/
  • Add new raw data there
• Simplify the config
• Add a scripts/describe_data.py (which will later supercede the figs_*.py scripts)
• Update Makefile to ensure the dependencies get propagated (i.e., don't use directories as targets)
• Small updates to iup/ files for better type hinting and bug tracking