* CircuitConfig, NodeSets, and SimulationConfig didn't have a top level
  docstring and thus sphinx `automodule` wasn't displaying them

* Many of the SimulationConfig were rooted in _libsonata, when they
  should be in SimulationConfig; this was refactored, however it has
  implications in the following projects:

* BlueCelluLab was update to work around the change
    https://github.com/BlueBrain/BlueCelluLab/pull/123

* SNAP tests have been updated to handle the different locations of
  SimulationConfig classes:
    https://github.com/BlueBrain/snap/pull/254