* PlaybackManager has been updated to workaround limitiations in
QtMultimedia
* PlaybackManager now sends the DeviceProfile to the server when
determining the playback url. This makes the Jellyfin server send
information back about transcoding.
* The DeviceProfile type has been changed from an QJsonObject into the
DTO generated by the OpenAPI descripton.
* A settings page has been added on SailfishOS that allows the user to
configure the PlaybackManager to their whishes.
* The DebugInfo page on SailfishOS now persists its settings (closes #8)
Besides MPRIS support, this also adds support for hasPrevious() and
hasNext() in several parts to determine whether the
player/playlist/shuffler has a previous or next item.