When using Editor Lite, store and access model directly on the instance instead of the editor itself
At the moment, app/assets/javascripts/editor/editor_lite.js
suggests that when we create a copy of an editor, we store the model for the underlying instance on the editor itself. This makes it impossible to create multiple instances with the same editor (share root options and tune on the instance level, for example) and requires the creation of new editor & instance couples for every editor we want to render on the view.
What this issue is about?
We need to move all references to the model
to the instance level. This includes editor's code, existing extensions (just one so far), and the existing code.