JSON Streaming helper

[stephenwf]

Oboejs works roughly like this (with some invented helpers):

// add empty `{id: manifestId, type: 'Manifest'}` to vault.
oboe(manifestId).node('items.*', canvas => {
  addCanvasToVault(canvas);
  return oboe.drop;
});

Which could stream in large manifests and their canvases. You could pause the stream until a user had scrolled or similar.

A general helper to help with streaming large JSON files would be very interesting!