Support removal of current/previous queue tracks

[antonk-dev]

Currently only upcoming tracks could be modified.

That work perfect for non-repeat mode, but in "repeat whole queue" mode it makes some stuff hard/impossible:

1. To remove already played tracks from repeat - you need to restart whole queue from beginning, drop tracks and return back.
2. More importantly - you can't remove first track without cleaning whole queue and rebuilding it again - as first track is always either current or previous.