Make the currying/specialization going on in render's arguments obvious.
Add component as first argument to render function.
In todo, replace message-handler by explicit send-message!.
In todo, replace dom-node arg by reacl.dom/dom-node.

... after renaming reacl.dom/dom-node-ref to reacl.dom/dom-node.
In todo, replace instantiate arg by reacl.core/instantiate.
Do in comments, products examples as in todo.

I.e. replace instantiate by reacl.core/instantiate,
and dom-node by reacl.dom/dom-node.
Bind component and local-state across all class/defclass clauses.

This means zapping a lot of arguments to clause functions in
class/defclass.

Also, the render class is just an expression now.