Keep device active

[MartijnVogelaar]

After a certain amount of time a paused device gets inactive and can thus no longer be controller. A solution should be found to fix this. This can either be by re-activating the device via the spotify-api(if possible?!?). Or by keeping it active by for example increasing and decreasing the volume every minute with 1 percent.

[RobLuzmo]

The active device is selected by default when no id is provided but by providing an id one can activate a device.
See spotipy-dev/spotipy#685 (comment)
So if the list of available devices is just 1 device, that id can be used, otherwise the last known id can be stored and used in case there's no active device.