ipython: 3.2 -> 4.0

[FRidh]

This PR features The Big Split

IPython 3 was the last major monolithic release of IPython containing all of the language-agnostic code, such as the notebook, which is moving under the new name Jupyter. As part of that process, we have created several discrete packages for each component - nbformat for the notebook format, nbconvert for the notebook conversion machinery, notebook for the HTML notebook application, etc.

This PR includes all dependencies needed.
ipython is now a small package. If you want to have the notebook, you need to install
pythonXXPackages.notebook
and if you want to have the qtconsole. you need to install
pythonXXPackages.qtconsole

Guess I now need to rebase onto master because of the earlier update to ipython 3.2.1

cc maintainers @bjornfor @jgeerds

[FRidh]

Note that this PR might also have consequences for packages outside python-packages.nix.
For example, there is a haskell kernel, cc @peti

[pSub]

There are conflicts, can your resolve them please?

[FRidh]

@pSub rebased to master

[FRidh]

@geerds gnome3.accerciser: init at 3.14.0 requires ipythonLight which I removed in this PR. Is the new ipython package sufficient? And if so, which version, 2.7 or 3.4?

[FRidh]

Built locally with nix-shell -I nixpkgs=. -p XXPackages.notebook XXPackages.qtconsole for all Python versions. Ran jupyter notebook and jupyter qtconsole successfully in all cases. I didn't use nox-review wip.

It would be nice to have this merged as soon as possible before anything breaks it again.

[FRidh]

The build failed due to running out of memory

[teh]

The nix style seems to be to have a space between [ and content. I.e. [ setuptools_scm pytest ] (and in all other locations)

[teh]

I've tested this with nox-review which generated 94 outputs successfully and I've executed a few things (e.g. ipython) and they seem to work fine. IMO this is ready to go.