Update older 'node' links

[arvoelke]

There are links to ?q=node/... in the following files that need to be manually corrected:

• software_index.md
• perception_index.md
• cognition/neural-cognitive-architecture.md
• cognition/modelling-problem-solving-in-ravens-progressive-matrices.md
• cognition/results.md
• cognition/cognitive-robotics.md
• perception/top-down-visual-feedback.md
• software/building-a-feedforward-network-part-3.md
• software/advanced-nengo-tips-and-tricks.md
• software/summary-of-available-tutorials-and-demos.md
• software/building-a-neural-integrator.md
• software/building-a-feedforward-network-part-2.md
• software/part-four-feedback-and-dynamics.md
• software/demo-learning-feedforward-transformations.md
• software/cogsci-2010.md
• software/building-motor-cortex-vector-representations.md
• software/nengo-model-archive.md
• software/building-a-controlled-integrator.md
• software/building-a-feedforward-network-part-1.md
• nef/statistical-inference.md
• nef/overview-of-the-nef.md

Additionally, the following links use the same sort of node numbering and thus need manual correction:

• NIPS demo