This was done to avoid running into [this
issue](https://github.com/vuejs/vue-cli/issues/3407)

Now every image attachment will be displayed on page top, just before
the actual content. This is enabled by default in the page model

Previous node sampling was a heuristic that may loop infinitely.
Now using proper CDF sampling. Corrected labels, we compute a MST
not a Steiner tree.