Extension to MPL to support the binding of artists to key/mouse events.
Remove connections for artists h1, h2, ...
Use clearall() to reset all connections.
Clear connections to all artists.
Use clear(h1,h2,...) to reset specific artists.
In case we need to disconnect from the canvas...
Trigger a particular event for the artist. Fallback to axes, to figure, and to ‘all’ if the event is not processed.