Cache old vnodes in the host element context

[manucorporat]

What?

• [ ] Store old vdom tree in the host element context
• [ ] Implement methods to recover the old vdom from HTML
• [ ] Refactor cursor.ts to use the old vnodes instead of DOM nodes
• [ ] Use old vnode / new vnode to implement class and style

Why?

• Solve host/parent conflict
• Remove dom operations completely from vdom walking, making it easy to execute in a worker
• Solve class/style rendering and conflicts
• Solve property removing problem

[mhevery]

Is this still relevant?