Notebook actually gets and holds ename, not etype
VideoIframe from YouTubeVideo (simplified) + VimeoVideo
Simplify InputSplitter by stripping out input_mode distinction
Allow IPythonInputSplitter to accept cell magics containing blank lines
using named keys and format string method + renaming VideoIframe to VideoIFrame
Separate InteractiveShell.input_splitter into two instances.

* input_splitter is used to detect when a cell is complete
* input_transformer_manager transforms completed cells

Closes gh-3178
Fix test failure in IPython.lib
Merge pull request #3203 from takluyver/cell-magics-wholecell

Separate InputSplitter for transforming whole cells

This allows cell magics to include blank lines once again (closes #3178).

InteractiveShell now has two input splitters:

- `input_splitter` is used to determine when a block of input is complete, so you can use a cell magic in the terminal by leaving a blank line at the end.
- `input_transformer_manager` is used to transform whole cells, so cell magics affect the whole of their cell.

I removed the similar concept of 'input modes' for InputSplitter, because it was bound to get conflated, and it made the code rather hard to follow.
Update link to extensions index
Merge pull request #3208 from benjaminfjones/patch-1

Update link to extensions index
IFrame + ScribdDocument
tabulation adjustment
generic IFrame(src, with, height), refactored YouTubeVideo, VimeoVideo, ScribdDocument
Fix inheritance_diagram Sphinx extension for Sphinx 1.2
Don't crash if README_STARTUP is missing

On Windows inside a py2exe'd environment, README_STARTUP does not
get copied into library.zip. Added a warning and a skip if
the file IPython/config/profile/README_STARTUP is missing.
Merge pull request #3211 from takluyver/sphinx-xfileref-removed

Fix inheritance_diagram Sphinx extension for Sphinx 1.2
Merge pull request #3212 from jusic/master

fix check_startup_dir inside py2exe

On Windows inside a py2exe'd environment, README_STARTUP does not
get copied into library.zip. Added a warning and a skip if
the file IPython/config/profile/README_STARTUP is missing.

closes #2563
Merge pull request #3186 from maximsch2/fix_etype_ename

Fix small inconsistency in nbformat: etype -> ename

We call this ename everywhere else, including in notebook files.
Merge pull request #3200 from 3kwa/master

add base IFrame class, and YouTubeVideo siblings, VimeoVideo and ScribdDocument
Starting to refactor heart beating of notebook kernels.