Cannot use the same instance to render nested mobiledocs

[gpoitch]

If you have a mobiledoc with a card that contains another mobiledoc, you cannot use the same renderer instance to render everything.

import MobiledocDomRenderer from 'mobiledoc-dom-renderer'

const renderer = new MobiledocDomRenderer.default()

const cards = {
  'some-card' : {},
  'some-other-card': {},
  'listicle-item-card': {
    display: { 
      setup: function (element, options, env, payload) {
        renderer.render(payload.mobiledoc, element, cards) // fixable by creating new MobiledocDomRenderer.default()
      }
    }
  }
}

const bodies = [{"version":"0.2.0","sections":[[],[[1,"p",[[[],0,"Opening text"]]]]]},{"version":"0.2.0","sections":[[],[[10,"listicle-item-card",{"title":"Item 1 title","primaryMedia":{},"mobiledoc":{"version":"0.2.0","sections":[[],[[1,"p",[[[],0,"Item 1 content"]]]]]}}]]]}]

renderer.render(bodies[1], null, cards) // => Uncaught HierarchyRequestError: Failed to execute 'appendChild' on 'Node': The new child element contains the parent.

I also think the API would make more sense if you set your card definitions as part of the renderer constructor instead of passing them to the render method every time.