repenser les fonction se sauvegarde, partage, chargement, import

remplacer l'existant par :
- save
- [x] auto-save (to url)
- to url : best for social media sharing.
- embed : for your website or blog.
- to human readable json file : best for long time compatibility, conversion, external editing
- to tiny file : so cool ! But useless.
- to gif : when you need gif animation.
- import
- [ ] Erase all before import
- from file(s)
- from url(s)