add shortcuts

[kupiqu]

very nice applet, but I miss shortcuts for play/pause, stop, seek forward and backward, next and previous track, and next source that I can use in playbar2. would you consider adding that feature?

[MurzNN]

I miss this feature too!, But have figured out that PlayBar plasmoid have great list of global shortcuts for controlling the media (even seek forward-backward), so as workaround I use they both together: PlayBar as mini-button to make the hotkeys working, and Media Controller+ as GUI controller.