Children fire event

Now when a container widget is displayed, the _handle_displayed method
of each of its children is fired.
fix pyreadline import in rlineimpl

it installs readline.py
Wrap nbconvert Markdown/Heading cells in live divs

Addresses https://github.com/ipython/ipython/issues/5206

This partially mimics the live IPython notebook layout, but is not a
complete solution.
Allow to pass option to jinja env

Mainly to pass cache_size=-1 while developping not to cache templates
Merge pull request #5200 from Carreau/jinja-no-cache

Allow to pass option to jinja env
Merge pull request #5212 from ahmadia/ahmadia/div_layout_fix

Fix mismatch of div/css in nbconvert and live notebook.
Merge pull request #5210 from minrk/pyreadline

fix pyreadline import in rlineimpl
ok, Running tab is working now
fix typo in method name
refresh of Notebook list should reload sessions
don't double-join the notebook path
Merge pull request #5197 from jasongrout/traitlet-notify

If there is an error comparing traitlet values when setting a trait, default to go ahead and notify of the new value.
remove reiterated repetitively redundant "actively"
fixup positional arg parsing in notebook app

- `ipnb .` triggers override of sub-config, even when the parent isn't changed
- `ipnb /path/nb.ipynb` sets notebook_dir to `/path`
write config instead of direct assignment from the command-line

Gross.
Make traitlets notify check more robust against classes redefining equality and bool

Before this change, numpy arrays caused problems since comparing two numpy arrays returns an array of truth values, rather than a single truth value.  This change guards against redefining the semantics of comparison by notifying on a trait change if the equality comparison returns anything other than an explicit True value.
Merge pull request #5220 from jasongrout/notify-check-2

Make traitlets notify check more robust against classes redefining equality and bool
Merge pull request #4985 from damianavila/closebrackets

Enable autoCloseBrackets in CodeMirror by default.
Changed children list to CTuple.

Also removed some unused refences in the widget code
and added support for tuples in the pack/unpack code.
Unset PYTHONWARNINGS envvar before running subprocess tests.

The extra warnings in the subprocesses were causing test failures.

Closes gh-5218