Detect (global) inhibitory connections.
Merge branch 'master' into inhibition
Merge branch 'multi-inputs' into inhibition
flake8 on ensemble.
Provide global inhibition values to the SpiNNaker executable.

 - EnsembleVertex has reference to a inhibitory_edge
   - edge is registered by the builder - only one may exist
 - EnsembleVertex has new regions for filter data and routing data for
   the inhibitory connection
 - General filters will now check that the connection they represent do
   not correspond to a x -> Neurons connection.  Such connections are
   ignored when building the filter and filter routing entries.
Typo and logical error in builder fixed.
Provide number of inhibitory dimensions and their gain to the ensemble.
Ensemble accepts inhibitory connections.

 - Ensemble has inhibitory connection filter
   - MCPL handler tries normal input, if this fails tries inhibitory input
   - Update code filters both normal input and inhibitory input
 - Ensemble update code computes inhibitory value and includes in neuron current
   **doesn't account for neuron gain**.
 - Inhibitory data added to SYSTEM region and regions 8 and 9 for filter and routing.
Clean header slightly.
Include gains in inhibitory input calculations.
Merge branch 'master' into inhibition

Conflicts:
	nengo_spinnaker/ensemble_vertex.py
Add inhibitory edge to graph.
Merge in from master.
Nearer to working inhibition.
Nearer working inhibition.
Merge branch 'inhibition' into inhibition2

Conflicts:
	nengo_spinnaker/builder.py
	nengo_spinnaker/edges.py
	nengo_spinnaker/ensemble_vertex.py
	nengo_spinnaker/utils/filters.py
	spinnaker_components/Makefile
	spinnaker_components/value_sink/Makefile
	spinnaker_components/value_sink/value_sink.c
	spinnaker_components/value_sink/value_sink.h
Include example for inhibition.
Global inhibition (sneaks in changes to builder).
Fix to ValueSinkVertex region size calculation.
Merge branch 'master' into inhibition2

Conflicts:
	nengo_spinnaker/builder.py
	nengo_spinnaker/utils/__init__.py
	nengo_spinnaker/value_sink_vertex.py