Rename attelo.fileNfold to attelo.fold and tidy up

Slightly clearer function names.
pep8 and pylint
Require --config
variant of common args without rels
feedback wrapper system (with Torpor(msg):)

- integrated into data reading
- this allows us to print a message before/after some slow action
attelo enfold: create folds and save them to json

Right now we don't have a way of consuming these folds, but we'll
get there.

Part of the idea here is also to make as much of our experiment
and archivable artefact as possible. Knowing what the folds are
seems pretty crucial.
tiny whitespace tweak