Adds a simple fading control to playlist sounds.
Once the module activated, you will notice an F control next to the playing button in the playlist directory. Clicking on F while the sound is stopped will play it and fade it in. Clicking on F while the sound is playing will fade it out, the F will blink in red until the volume is down.
N.B. The track is stopped as soon as the volume is 0 for the person that clicked. If this person has already the volume set to 0 it will not fade at all.