Not sure if I want nox_core -v in nox.py - it's useful for debugging.
ripcordtest.py (and grid.py) still depend on routing, which I haven't been
able to test yet.
Unfortunately, I can't test this at the moment since nox seems not to
be able to find the routing module.
Added/renamed examples: grid.py, tree1024.py
Added -v flag to nox arguments, so we have some chance of figuring
out why nox is dying, as it generally is.