Fix for #3719

%-d is not a valid strftime format on windows.
add delay to autosave in beforeunload

allows forceful 'discard changes' by reloading the page and dismissing the warning,
which @fperez really wanted today.
my attempt to fix #3735

an alternative to this would be to do something like
`\DeclareGraphicsExtensions{.pdf}` in the preamble
better message when notebook format is not supported

Different messages for bad version and bad JSON.

closes #1592
remove notebook read-only view

it is largely broken, and had problematic security issues.
Add link_or_copy to IPython.utils.path
Use link(2) when possible in nbconvert
Fix a couple typos
Add cwd to sys.path
This makes transformers and filters in the cwd load
from dotted object names.
Better name `init_syspath`
py3 doesn't have nested, py2.6 doesn't have multiple context managers
document Ctrl-C not working in ipython kernel

This closes #2049
add signature_scheme to Session and connection files

also change default hash to sha256 instead of md5, since md5 is bad.
(this is the main motivation)
propagate signature_scheme config to parallel connection files
document the wire protocol
Provide a more useful error for invalid use case.
The previous help statement was not very usefull for users who
don't know how to use nbconvert (ironically, the exact set of
users who would encounter the error).
Allow notebook filenames without their extensions
Added rm_math_space to markdown cells in the basichtml.tpl to be rendered ok by mathjax after the nbconvertion.
Merge pull request #3760 from jdfreder/auto_nb_ext

nbconvert: Allow notebook filenames without their extensions

allows `ipython nbconvert fig` to render `fig.ipynb`
Moved print description and examples into default help output
Worked with @ivanov