Hardcode exception for __pycache___
set default permission to 775 with makedirs
require print_method to be a bound method

closes #4990
add _valid_formatter

for determining whether a method is valid

should properly reject unbound methods of both compiled and Python classes, and allow any other Python callable.
don't allow LazyConfigValue on private names

avoids populating Config objects with `_repr_foo_`, etc.
add regex support to AssertPrints
add IPython.html.nbextensions.install_nbextension

for installing files into IPYTHONDIR/nbextensions
add `ipython install-nbextension` entrypoint
add install_nbextension at top-level IPython.html
support URLs and zip/tarballs in install_extension
typo
rewrite _valid_formatter

- explicitly forbid method_descriptor
- explicitly allow builtin_function
- use inspect.getcallargs for any other callable
allow installing nbextensions with symlinks
add check_nbextension
add IPython.load_extensions in js
Merge pull request #5053 from jdfreder/js-test-refact

Move&rename JS tests
Merge pull request #4977 from minrk/scp-mkdir-p

ensure scp destination directories exist (with mkdir -p)
Merge pull request #5066 from minrk/pylab-examples

remove (almost) all mentions of pylab from our examples
flush replies when entering an eventloop

avoids possible hangs when the GUI eventloop prevents queued replies from being sent
add utils.get_data

for extracting *decoded* items from $('body').data