Default behaviour added: play random file in playlist
Playlist selection code moved to setNewPlaylist() function.
Implemented newPlaylistButton click event.
Implemented handler on_restartButton_clicked
Added playlist clear before inserting new media: otherwise old playlist media would still remain.
Added nextMediaButton: onclick event connected to next() slot of playlist
Deleted player.stop() and player.play() in on_restartButton_clicked() : was useless.
setNewPlaylist() is now a slot connected to nextMediaButton onclick event.