Allow remount of nodes

[akheron]

Find out whether it could be possible to remount nodes (even if only in some limited cases).

This would the useful e.g. with combinators like:

defaultTo(
  property,
  (value) => { 
    // if not undefined
  },
  <span>loading...</span>
)

Here the <span> would be remounted when the value of property changes back to undefined