Add structural layering to Lively4 Morphs (or arbitrary DOM elements) #43
Description
Not sure whether this should go here or into the Lively repository...
For demo purposes, we could implement structural layers and an example in the new Lively, like it was in the old one. By the way we can evaluate if the LayereableObjectTrait can or should be refactored into a mixin (like presented as an idiom for ES6 classes).