Spotify tracks that are not playable have now a "not allowed" cursor when hovered.
Moreover, the Bulma CSS class is now used for clickable items instead of a custom one.
If a Spotify playlist is containing unplayable tracks (e.g., wrong market), the position of the subsequent tracks in the playlist must be changed accordingly.
Moreover, the album property was provided for no reason.
Additionally set market query parameter for albums and tracks. According to the spotify documentation, this should not be necessary, as the market for the user account should be used if not set.
