[pymvpa] How to train a SurfaceQueryEngine?

[Swaroop Guntupalli]

Hi Nick,

I am trying to use SurfaceQueryEngine, but looks like training
requires a dataset with node_indices as fa. How do I generate a
dataset with surface information? Is there a helper function to
achieve that?

Since SQE is node-to-nodes mapping, can we skip training with volume
dataset altogether?

Thanks,
Swaroop