add sidebar
show all playlists on sidebar
add sidebar css
add PlaylistLoader
save playlist
Refactor
Clear selected tracks when currentPlaylist changed
Merge branch 'show-playlists'
show draggable elements
doubleclick to play
drag to show insertion space
add onDragEnd / move tracks on drop
do not recognize quick clicks on different elements as doubleclick
Merge branch 'draggable-selector'