Merge pull request #25 from flowersteam/pools-v2

Pools v2
Temporary backup before using DataSet in third_party.models instead of
scipy (simultaneous handling of forward and inverse models already
implemented in DataSet)
Add nearest_neighbor sensorimotor model
Add doc to the nearest_neighbor sensorimotor model
Merge branch 'master' of github.com:flowersteam/explauto
Update the notebook.
Merge branch 'master' into poppy-xp