Track Nengo upstream.
Track Nengo upstream.

(cherry picked from commit 2593f8a1df0621c2061da4d1c913b552a4a1ea72)

ctn-archive/nengo_spinnaker_2014,ctn-archive/nengo_spinnaker_2014,ctn-archive/nengo_spinnaker_2014,ctn-archive/nengo_spinnaker_2014