Improve Windows start menu shortcuts
Remove PyLab mode shortcuts for Notebook and QtConsole
Key the root modules cache by sys.path entries.

Instead of a single root modules cache, cache in a dict the list of modules
associated with each sys.path entries (except $PWD).  On future import
completions, create the list of completions by merging the appropriate cache
entries (while updating the cache if sys.path changed) and adding in the
modules in $PWD as well.  This allows the completer to keep up with multiple
Python installations, virtualenvs, etc.

Right now the root modules cache grows indefinitely.  It may be worth
implementing a LRU cache, a la functools.lru_cache.
BUG: Fix the set and frozenset pretty printer to handle the empty case correctly.
Add missing import in IPython parallel magics example
Merge pull request #3172 from ogrisel/missing-import

Add missing import in IPython parallel magics example
Use base documentation URL
Merge pull request #2635 from cgohlke/windows-startmenu

Improve Windows start menu shortcuts

* Create Windows start menu shortcuts with better names.
* Add shortcuts for IPython Notebook and online documentation.
* Add icons for IPython console and notebook.
* Apply PEP8 to ipython_win_post_install.py.
* Tested on win32-py2.7, win-amd64-py2.7, win-amd64-py3.3, Windows 8.
Fixed minor typo
Minor typo, casing, and plurality fixes
Merge pull request #3173 from rgbkrk/doc_fix

Little bits of documentation cleanup
Added missing s
Merge pull request #3175 from rgbkrk/patch-1

Added missing s
better UsageError for cell magic with no body

closes #3179
backport If-Modified-Since fix from tornado

See facebook/tornado#713

closes #3177
clarify %%file docstring

there was a leftover mention of `-f`, which doesn't actually exist.

see #3178
add path.get_ipython_cache_dir to retrieve a cache directory
use cache directory for cython files

closes #3009
Merge pull request #3184 from juliantaylor/cython-cache

Cython cache
Notebook actually gets and holds ename, not etype