Allow filename with extension in find_cmd in Windows.

closes gh-3316 (hopefully)
Add a mode to exec code in %debug magic
Document the new usage of %debug
Drop patch for compatibility with pyreadline 1.5

Closes gh-1307
Set calling program to the empty string, when argv not in sys

It might happen, then the sys module has no argv, when embeding IPython
into other programs with IPython.embed(). In that case, just set the
calling program to "" or other logic in IPython will crash - for
instance when checking for command line arguments.
add create.Cell and delete.Cell js events

The events fire after the cell has been created or deleted.

closes #3154
Added shorcuts to split cell, merge cell above and merge cell below.
don't blacklist builtin names

it is wholly appropriate for a class to have a `format` trait, or similar, but Config prohibits it.

This just removes that prohibition.
Corrected a typo in the format string for strftime
update config builtins test
Added '-' as a shortcut for splitting cells.
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
Markdown in heading cells (take 2)

small typo prevented the previous implementation from working.

This also moves the rendering to the 'render' method,
away from set_rendered.

closes #3053

(again)
truncate invalid multi-line headers
merge heading lines

markdown headings must be a single line
remove unnecessary heading-anchor

residue from when the heading text itself was a link

the id is on the header tag itself,
and the link is anchor-link
allow extra pandoc args
use mathjax-style for math passing through pandoc to html
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