Allow zero sized regions (don't reserve or write to them).
Allow no-decoder ensembles, transmit decoded values after neuron updates.
Merge pull request #36 from ctn-waterloo/no-decoders

Ensembles with no Decoders, Update loop modifications
Merge branch 'refactored-vertices3'

Conflicts:
	nengo_spinnaker/utils/vertices.py
	spinnaker_components/ensemble/ensemble-update.c
Fixes to transmitted multidimensional values from ethernet.

(cherry picked from commit ea91dfb0daf828b21418060fa4a22fa7eebe217e)
[Bugfix] SDPReceiveVertex reserved too little space for output keys.

(cherry picked from commit a3d7ddb62bb446f3eef9abef78c467d7d2c9da54)
Fix recursive bug in totuple.  Not sure how it got there.

(cherry picked from commit ae1f7beb5188eaf09fc3f7efc1061a15a12aecf2)
Remove spurious print from filters processing.
Example transmits sin rather than constant value.
bitarray is an optional extra.

Without bitarray, utils.probes.SpikeProbe is None, this is caught by the
builder and an error is raised if the user tries to make use of this
functionality.
Add requirements.txt, modify docs conf accordingly.

Pull in Nengo using Git, modify when a Pip release is made.
Correction to requirements.txt
Update requirements.txt
Update requirements.txt
Update requirements.txt

Include bitarray.
flake8 and documentation for simulator.
Further documentation on Nodes.
Include images in doc.
Bugfix to decoder equivalency check.
Fixes to SpiNNlinkUSB, FilterVertex.