Networks created using nengo_spa are hard to understand

[Seanny123]

Previously, in nengo.spa thalamus routing populations would be "magically" rolled in the spa.State which made the network mildly more readable. However, this no longer happens nengo_spa.

Jan and I discussed this and I propose that when a spa.Network is present, it should be possible to toggle between two views:

1. A routing view, where the connections to the Basal Ganglia and from the Thalamus are coloured differently. Additionally, the colour of the Thalamus connections can be enabled to change with inhibition, thus visualizing the flow of the information through the network.
2. A router-less view where the connections into the Basal Ganglia and from the Thalamus are hidden.