Merge with upstream changes.

Minor changes to the mcdriver.py example.

Fixed most of the examples. A few still don't work, but this is a start.

Adding examples from ipython1-dev to docs/examples/kernel. These examples show how to use IPython for parallel computing. I need to update the import statements and make sure they work with the merged code. But here they are.

Merging in Fernando's testing stuff.

Made ipcluster not use security by default. We need to revist this as ipcluster will eventually need security. But for now this should be fine as ipcluster only really works for starting things on localhost.

Added Nose support for IPython doctests and extension modules.

More testing cleanup...

Testing cleanup of old/conflicting stuff.

Refactor of platutils for cleanup. Reduces duplication of common functionality, os-specific modules only implement their own routines and the common code is provided by the top-level public module.