clean demo
[gardening] remove unused polyfill
add snapping on drag'n'drop of the zonard, update example
use a local animationFrame polyfill instead of a package
add snap notification on move events triggered by zonard
[gardening] slight calculus simplification
simplify calculus, standardize rotated center positions transmitted
add bBox to the data transmitted (when possible)
[fix] change snap notification, fix trailing whitespaces