Rerun notebook before editing it.
Add an example of Context.register.
Add mpi-only example.
Add an mpi-only example.
Add and edit some comments and text.
Remove basic_demo.py.

features.ipynb eclipses it I think.
Remove old julia-set example.
Remove some extraneous examples.

I think features.ipynb eclipses all of these.
Move distarray protocol stuff into its own folder.
Rename example folders to use underscores

...instead of dashes.  So they can potentially be used as subpackages.
Update the module docstring.
Add help text with argparse.
PEP8 and PEP257.
Tweak an error message.
Move argparse parser to under the name=main clause.
Add argparse CLIs to pi_montecarlo.
Remove some unused imports.
Add a cli for benchmark.py.
Make the examples subpackages.
Rename seismic-volume.ipynb -> seismic_volume.ipynb.