This requirements file contains a pathological case where we have to
step through all the versions. I'm putting it in git to make it easier
to collaborate on it.
Remove a dev annoyance: This makes the development paths shorter, e.g.
`scripts/benchmarks/requirements/all-kinds.in` to
`scripts/requirements/all-kinds.in`. The requirements are also shared
between different tasks and not only used for benchmarking.
konstin