message: Accept fields and market parameters in Spotify.playlist and Spotify.user_playlist respectively
diff: @@ -480,19 +480,25 @@ impl Spotify {
  self.convert_result::<PublicUser>(&result.unwrap_or_default())
  }
  - //TODO: fields
  ///[get playlist](https://developer.spotify.com/documentation/web-api/reference/playlists/get-playlist/)
  ///Get full details about Spotify playlist
  ///Parameters:
  ///- playlist_id - the id of the playlist
  ///- market - an ISO 3166-1 alpha-2 country code.
  - pub fn playlist(&self, playlist_id: &str, market: Option<Country>) -> Result<FullPlaylist, failure::Error> {
  + pub fn playlist(&self,
  + playlist_id: &str,
  + fields: Option<&str>,
  + market: Option<Country>) -> Result<FullPlaylist, failure::Error> {
  let mut params = HashMap::new();
  + if let Some(_fields) = fields {
  + params.insert("fields".to_owned(), _fields.to_string());
  + }
  if let Some(_market) = market {
  params.insert("market".to_owned(), _market.as_str().to_owned());
  }
  - let url = format!("playlists/{}", playlist_id);
  + let plid = self.get_id(Type::Playlist, playlist_id);
  + let url = format!("playlists/{}", plid);
  let result = self.get(&url, &mut params);
  self.convert_result::<FullPlaylist>(&result.unwrap_or_default())
  }
  @@ -545,12 +551,16 @@ impl Spotify {
  pub fn user_playlist(&self,
  user_id: &str,
  playlist_id: Option<&mut str>,
  - fields: Option<&str>)
  + fields: Option<&str>,
  + market: Option<Country>)
  -> Result<FullPlaylist, failure::Error> {
  let mut params = HashMap::new();
  if let Some(_fields) = fields {
  params.insert("fields".to_owned(), _fields.to_string());
  }
  + if let Some(_market) = market {
  + params.insert("market".to_owned(), _market.as_str().to_owned());
  + }
  match playlist_id {
  Some(_playlist_id) => {
  let plid = self.get_id(Type::Playlist, _playlist_id);
  