Sækja cfcli 0.18.0

This release writes a lighthouse configuration file straight to a swarm.

### New features

• **Lighthouse configuration files for a swarm** — `swarm lh write` and
`swarm lh check` take a YAML file with `-i/--input`, as `lh config write -i`
and `lh config check -i` do for one Crazyflie. The file is used instead of
the stored configuration the swarm names, for example one from
`lh config read` or the Crazyflie client. `write` skips the Crazyflies that
already have it, as before. See
[docs/swarm.md](docs/swarm.md#lighthouse).
([#42](https://github.com/bitcraze/cfcli/issues/42))

```text
$ cfcli swarm lh write -i my_setup.yaml
Lighthouse config from my_setup.yaml：base stations 4, 5, 6, 7
CF-05：written and stored in flash
CF-06：up to date
```

### Improvements

• **`swarm lh` loads the configuration first** — a missing or broken file, or
an unknown stored configuration, fails at once, before any Crazyradio is
opened.
• **`swarm lh check` suggests the right `write`** — when Crazyflies differ, the
`swarm lh write` it suggests includes the `--config` or `-i` that was given.
It used to suggest plain `swarm lh write`, which writes the configuration
the swarm names.