* Support `position_ms` optional parameter in `start_playback`
* Add `requests_timeout` parameter to authentication methods
* Make cache optional in `get_access_token`
* Support for `playlist_cover_image`
* Support `after` and `before` parameter in `current_user_recently_played`
* CI for unit tests
* Automatic `token` refresh
* `auth_manager` and `oauth_manager` optional parameters added to `Spotify`'s init.
* Optional `username` parameter to be passed to `SpotifyOAuth`, to infer a `cache_path` automatically
* Optional `as_dict` parameter to control `SpotifyOAuth`'s `get_access_token` output type. However, this is going to be deprecated in the future, and the method will always return a token string
* Optional `show_dialog` parameter to be passed to `SpotifyOAuth`
* Both `SpotifyClientCredentials` and `SpotifyOAuth` inherit from a common `SpotifyAuthBase` which handles common parameters and logics.
* Support for `playlist_tracks`
* Support for `playlist_upload_cover_image`
* `user_playlist_tracks` doesn't require a user anymore (accepts `None`)
* Deprecated `user_playlist` and `user_playlist_tracks`
* Fixed broken examples in README, examples and doc
* Allow session keepalive
* Bump requests to 2.20.0
* Fixed inconsistent behaviour with some API methods when
a full HTTP URL is passed.
* Fixed invalid calls to logging warn method
* Support for `playlist` to get a playlist without specifying a user
* Support for `current_user_saved_albums_delete`
* Support for `current_user_saved_albums_contains`
