Fixes #720.

setup_preprocessor is a contextmanager that handles setting and cleaning
up attributes needed by the rest of the execution logic (specifically
self.nb, self.km, self.kc).

start_new_kernel was previously a callback function and is now a
separate method used inside setup_preprocessor.

This also introduces a dynamic default for the `kernel_name` traitlet
that checks if self.nb is defined to see if it has a kernel name, and
otherwise will raise an AttributeError (since that means it is being
relied upon without any way to know which kernel is to be used.

moved _display_id_map help inside the declaration instead of comment

unified named imports from traitlets

Feature mentioned in
nteract/papermill#135 (comment)

Changed 'ouptut' to 'output'.

Per GitHub issue #837, document the '--inplace' command line
flag.

Drop support for python 3.3

I noticed that absolute paths do not work since a URL is constructed from the directory, but this was not clear from the documentation. If someone has a better wording, I'll be glad to change it. 

Also, this should updated in https://nbconvert.readthedocs.io/en/latest/config_options.html but the 'Edit on Github' button is broken.

Pass config to kernel from ExecutePreprocessor for configurable kernels

Update widgets CDN for ipywidgets 7 w/fallback

WIP. Allow the execute preprocessor to make use of an existing kernel

Move onlyif_cmds_exist decorator to test-specific utils

closes #846

properly treat JSON data

Add note about local reveal_url_prefix

Support for \mathscr

update font-awesome version for slides

No need to check for the channels already running

populate language_info metadata when executing

I was working on jupyter/notebook#3879 and it
looks like the intended way to determine whether the exporter should
show up in the list generated by the notebook server was by checking
`export_from_notebook`, but it isn't defined for any of the builtin
exporters.

The docs also say this specifies a friendly name for the exporter. In
the PR mentioned above, I used the name defined by the entrypoint to key
the exporter. It sounds like maybe we should use the value in
`export_from_notebook` instead, so I've made them match, but perhaps
it's confusing to have a "name" for the entrypoint in two places.

Fix minor typo in usage.rst

Add export_from_notebook

If set, use `nb.metadata.authors` for LaTeX author line

handle embedded images in html converter

Don't remove empty cells by default

Document --inplace command line flag.

Side question: are we ready to drop 2.7 ?

Add python_requires metadata.

A couple of typos

Fix api break

Fix Unknown exporter "ipynb": Did you mean "notebook"
Closes #3769

…3769

Fix Unknown exporter "ipynb"

No input flag

Added long description to setuptools for new pypi page

Release 5.4

Release changelog 5.4

See http://www.sphinx-doc.org/en/master/usage/restructuredtext/directives.html#directive-code-block

Updated release instructions based on 5.4 release walk-through

DOC: Add missing language specification to code-block