pylab-> matplotlib
remove some other occurences of pylab
remove again a few other occurences
cleanup a few remaining mentions of pylab in docs
cleanup pylab deprecation

extra substitution was unnecessary because argparse supports passing args with spaces
don't recommend `ipython notebook --matplotlib`
Merge pull request #4 from minrk/pr/3816

Finish up PR #3816
Merge pull request #3816 from Carreau/depylab

s/pylab/matplotlib in docs

Remove most remaining mentions of `--pylab` in the docs.