make @interactive decorator friendlier with dill

sets the decorated function globals to main,
in addition to just the module name.

This helps dill treat it as if it were defined locally,
and the function actually behaves the same locally as it does on engines.
add to dill example notebook

because we can't write proper tests with dill, due to side effects.
still allow @interactive on Classes
fix typos in development docs
fix typos in parallel docs
Merge pull request #4711 from ivanov/typos

some typos in the docs
Tabs converted to spaces for #4643
Merge pull request #4696 from minrk/etree-fail

don't do anything if add_anchor fails

invalid content shouldn't necessarily kill nbconvert
Merge pull request #4691 from minrk/no-localhost

subprocess output will be unavailable, but the process will not die.

closes #4689
Include qt.console.frontend_widget in docs
Example of adding input transformers.

Closes gh-4709
Standardise some module docstring first lines
Fix header levels in technical description of config
Update inputsplitter docstring
Downplay the need for pyreadline on Windows.

Closes gh-4544
Add failing test for saving kernel history on Python 2
Fix ``%history -f foo`` in kernel.

Closes gh-4582
Remove input_prefilter hook

Our code already doesn't call this hook (as pointed out in gh-4709), and
probably hasn't for some time, so it seems ~no-one is relying on it. We
have much more powerful APIs to do the same thing.
Docstring update for Sphinx IPython directive.
restore use of tornado static_url

instead of jinja macro that doesn't write hashes

closes #4714