Blender Git Loki

Progress towards making material output the same as the python exporter.

The python exporter was stricter about what Principled BSDF node it
would use -- it only wanted one directly attached to the Material Output.
Also, the Python exporter sets the ambient to (1,1,1) if no reflections.
And there was a mistake in how the C++ exporter set the illumination model.

Also printed out the components in the same order as the python one,
for easier comparison.