Notes editing

[makovako]

• [x] allow editing of existing notes
• [x] allow deletion of existing notes
• [x] allow deletion of whole note
• [x] allow renaming of a note
  • nothing to rename, filename can be named when exporting
• [x] allow appending new notes (watching video again), let user choose if append or overwrite existing one
  • user will see the existing note and can edit it