Add scipy stack to python

[a-y-khan]

Add the scipy stack (includes numpy) to the python external. Might be tricky on Windows, and Mac OS X because of the framework setup.

[thoth291]

Why don't you just let users to link their custom python modules from wherever they have them by using this line in their python script:

#insert(0,... if you need to make your custom packages discoverable first
sys.path.append('/location/of/my/personal/site-packages')

It's a normal way of adding packages in the embedding world...