Enhance playlists with universal pause intervals between tracks

Continuously listening to every single track you've managed to put in playlist without proper pauses between tracks can easily become irrelevant to your life style or even just unhealthy.

I personally encountered more excitement from differentiated pauses in some videogames than remain silent sound after another great music, so I could get in sync with repetitive playback (even with few tracks).

But that's not all I wanted to notice. There is already some workaround where you tackle playlist's source code by adding fixed-size pauses as separate tracks. This one can be automized to have an option to save manual pauses created via UI.

Main concern here is that proper pausing between tracks is not yet supported out-of-the-box, i.e. without modifying playlist externally. And manual adding pauses through UI can be somewhat way more complex for everybody, so I recommend to:

1. implement custom pausing per whole playlist that is recognized according to modified spec with root tag's attributes once playlist loaded,
2. escalate user interface for global pausing and intervals based on playlist.

I guess it would be good starting with global inter-pausing mechanism and making it an accessible part of controlbar near "shuffle", that opens window with three options:

1. fixed interval (from 0 to infinity),
2. dependent (based entirely on track's duration, within min and max boundary),
3. random (min-max).