coordinate migration to python3 with GRB package migration
Coordinate with @nickb on migration of quicklooks to python3. Ideally it will be done in sync with the rest of the GRB package, to avoid having to bundle two ShellB3 builds with the v1.1 release (which I think is actually done currently but would prefer to avoid in the future).
See cspp-geo-grb-grbr#1.