no longer necessary to do late borrowing as the Evento library is now hidden inside the IIFE that wraps the whole Maria distribution. That IIFE means it is not possible for application developers to change how the Evento on, off, and purge functions work. Therefore eager borrowing is fine.
Expose the hijos Leaf and Node constructors so that they can be used for other purposes by application developers. For example, creating LeafModel and NodeModel constructors.
increment version