Add Origin Checking.
Get rid of exc_info as there isn't an exception.
Indicate Py3 vs. Py2 codepath.
Use *args, **kwargs, log.warn
Performing check only on open.
Verify that headers are set, explicitly
Name change to same_origin
s/==/is/
Handle variations of name for origin
Don't enter edit mode when changing cell type and preserve renderd.
alt+enter should always insert below
shift+enter and ctrl+enter swapped.
Fixing help strings for shift|ctrl+enter.
Fixing tests from shift and ctrl enter swap.
Merge pull request #4916 from ellisonbg/modalbehavior

Fine tuning the behavior of the modal UI

swap back shift- and ctrl-enter, to their rightful places.
Merge pull request #4845 from rgbkrk/origin_host

Add Origin checking for websockets.
mention that pexpect ships in IPython.external

and only check for it on posix
only put Python major version in wheel tags

results in 'py2-none-any' instead of 'py27-none-any'.

This is supported by pip and PEP 425, but not available from bdist_wheel by default.
exclude notebook checkpoints from manifest
platform-dependent requirements

in bdist_wheel