for dumping and restoring use new 'note restore' that is similar to 'note create', but with hard-coded id

However, it seems that pressing alt_l makes Pd swallow other keys

make sure to move/copy only selected _active_ notes (ignore inactive, even if they're are marked)

 * make a range selection only when clicking on empty space
 * allow to add multiple ranges
 * toggle selection of single notes when shift-clicking notes

finally figured out how to make 'note change duration' interaction work correctly while respecting boundaries

grey out scroll buttons when reaching boundary; add scrollup, scrolldown, pageleft, pageright receives