Pep8 numpy lib

Apply pep8 and pyflakes to the files in numpy/lib and numpy/lib/tests. Some long lines found in the references and examples persist and require more work to bring them into conformance. I'm not sure how to do that for long urls.

Some of the fixes motivated by pyflakes look like possible coding errors. Most of those are unused variable warnings, and when they looked a bit suspicious I commented them out with a `Fixme` tag for later audit.