Upgrade to steal 2.0

Support HTTP/2

Uses new done-mutation for incremental rendering

This adds support for incremental rendering through HTTP/1. This works
by attaching a `<link rel=preload>` to the document which will preload
the rendering instructions, which happens in place of the H2 PUSH.
Closes #582

Allow incremental rendering to occur over HTTP/1

set of TextNodes. This is a new API provided by done-mutatation. Doing
this will ensure that we keep track of when text nodes were part of the
original parsed document and which are added layer. This makes it so
that we send the correct indices to the client layer.

In done-mutation 2.0 the collapseTextNodes option is no longer
necessary. So this removes it and uses ir-clone instead for
serialization.

For incremental rendering we need to split up TextNodes so that they are
in the IR document. This way when we start doing mutations we can
correctly identify which Nodes need to be updated.

Use ir-clone to serialize incremental rendering document

We should be serializing the iframe document using ir-clone in order to
ensure that its comment nodes are injected.

Serialize iframe document

When we start out own MutationObserver stop listening to mutations using
nodeIndex. This prevents us from getting indices that are updated too
soon.

Use nodeIndex.reindex() to reindex after creating the IR frame

This switches the toggle so that incremental rendering is the default.