Weighting for songs in playlists on shuffle.

[Alex36346]

Allow users to add a weight to songs (a number that increases or decreases the likelihood of a song being played) in playlists to be more likely to be played or played more often whilst the playlist is in shuffle mode like a weight system for songs.

For example for default songs would have a weight of 10 and increasing it makes it more likely to be played and decreasing it would decrease the likelihood of it being played.