Add failing test for gh-3547
Simplify caching of modules from %run-ing scripts.

Previously, we cleared and re-used a single FakeModule instance in which to
run cells, and cached copies of the modules' namespaces to prevent them from
being cleared. Now, we cache one FakeModule instance per script file, clearing
it and re-using it if the same script is re-run. This seems more robust.

Closes gh-3547
Another passing test :-)
Minor tweak to test for Python 3
Mention API changes in whatsnew doc
Corrected a typo in the format string for strftime
Update docstring of new_main_mod() method
add extra_config_file

and `--config` alias

for loading a single extra config file, e.g.

    ipython notebook --config mycfg.py

which will be strictly in addition to, and at higher priority than, existing config files, profiles, etc.

Note that the loading code hasn't changed, it's just indented to put it in a for-loop.
update config_file_specified in kernel app

it's a set now
a nicer error message when using %pylab magic

If the user specified an unsupported backend, there was no indication
for what the valid names were. Error message prior to this commit:

    In[1]: %pylab xxx
    ERROR: Backend u'xxx' not supported.

after this commit:

    In[1]: %pylab xxx
    ERROR: Backend 'xxx' not supported. Supported backends are: gtk inline osx qt qt4 tk wx
check for markdown no longer needed, closes #3610

After #3582 was merged, we no longer depend on a python version of
markdown
Merge pull request #3555 from takluyver/i3547

Simplify caching of modules with %run.

Previously, we cleared and re-used a single FakeModule instance in which to run scripts, and cached copies of the modules' namespaces to prevent them from being cleared. Now, we cache one FakeModule instance per script file, clearing it and re-using it if the same script is re-run.

Closes #3547, and fixes another test that was marked as a known failure.
Merge pull request #3611 from ivanov/no-markdown-check

check for markdown no longer needed, closes #3610

After #3582 was merged, we no longer depend on a python version of
markdown.
Merge pull request #3586 from breisfeld/master

Corrected a typo in the format string for strftime the sphinx.py transformer of nbconvert
updated .mailmap
fix regular expression for ANSI escapes

wouldn't catch `\x1b[01;`, only `\x1b[0;` or `\x1b[1;`.

closes #3614
Add examples for interactive use of MPI.

Closes #2934.
Merge pull request #3615 from minrk/ansilinux

Fix regular expression for ANSI escapes, which wouldn't catch `\x1b[01;`, only `\x1b[0;` or `\x1b[1;`.

Closes #3614.
Merge pull request #3616 from fperez/interactive-mpi

Add examples for interactive use of MPI.
Merge pull request #3612 from ivanov/mailmap

updated .mailmap