- [playback] Add `--volume-range` option to set dB range and control `log` and `cubic` volume control curves
- [playback] `alsamixer`: support for querying dB range from Alsa softvol
### Changed
* [audio, playback] Moved `VorbisDecoder`, `VorbisError`, `AudioPacket`, `PassthroughDecoder`, `PassthroughError`, `AudioError`, `AudioDecoder` and the `convert` module from `librespot-audio` to `librespot-playback`. The underlying crates `vorbis`, `librespot-tremor`, `lewton` and `ogg` should be used directly. (breaking)
- [connect, playback] Moved volume controls from `connect` to `playback` crate
* [connect] Synchronize player volume with mixer volume on playback
- [playback] Make cubic volume control available to all mixers with `--volume-ctrl cubic`
- [playback] Normalize volumes to `[0.0..1.0]` instead of `[0..65535]` for greater precision and performance (breaking)