Plugwise

- Add `domestic_hot_water_setpoint` to the output. Will become an additional Number in Plugwise(-beta).
- Create separate dicts for `domestic_hot_water_setpoint`, `maximum_boiler_temperature`, and `thermostat` in the output.
- Change `set_max_boiler_temperature()` to `set_number_setpoint()` and make it more general so that more than one Number setpoint can be changed.
- Fix a cooling-related bug (Anna + Elga).
- Improve `set_temperature()`function.
- Update the testcode accordingly.

- Smile Adam & Anna: add cooling-mode detection, presence and operation (fixes 171)
- Link to plugwise module [v0.15.7](https://github.com/plugwise/python-plugwise/releases/tag/v0.15.7)

- Update code to Core 2021.12 requirements

- Smile:
- Clean up and improve code
- Bugfix via linking to plugwise module [v0.15.4](https://github.com/plugwise/python-plugwise/releases/tag/v0.15.4)
- Fix test-code: don't use protected parameters