game-of-life: Initial living-neighbouro tests

It can't properly run backwards yet, so test only the forward run.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
README: Add links to the arithmetic explorations

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
playground: Require all namespaces

To make it easier to play live, include all the namespaces.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>