VOR related models

[andrewgait]

This PR adds some examples based upon the new models developed in https://github.com/SpiNNakerManchester/sPyNNaker/pull/1152. There are probably too many examples here in the directory at present and it could easily be simplified if needed.

Edit: in fact, most if not all of these scripts are repeated in vor_cerebellum, so this PR can probably be closed if the others are accepted.