fixes tests/unboxed-spark

• taken initially from the existing one that require()s from
  smooth-plotter and synchroniser, for obtaining the Dygraph
  “global” in a module system
• some ways to import put it as .default though so use that
  if .NAME is absent but .default is defined
• apply this to all extras, fixing (#848) (#989) (#1009)
• drop redundant closure where applicable, suitably label otherwise
• label all functions here

import release notes as written on GitHub in Markdown, for the
last release, prepending a first-level heading with the release
name, which for us equals the tag, only; we shall be using this
file to paste as future release notes, *and* we’ll be generating
the docs/versions.html file from it; this can be achieved by
using a subset of Markdown only