Hypnotoad example grids

v1.1: Found that the LDN topology had the opposite psi sign to all the rest. In this version the sign is flipped so that all the grids avoid negative dx and J. v.1.0: This archive contains Hypnotoad grids in 6 topologies: Upper single null Lower single null Connected double null Upper disconnected double null Upper disconnected double null (secondary far from plasma edge) Lower disconnected double null These are generated with and without Y boundary guards, and are uploaded here for testing purposes. They were created using the tokamak_example.py script in Hypnotoad (https://github.com/boutproject/hypnotoad/blob/master/examples/tokamak/tokamak_example.py).