DOC: typos + rewording in examples/notebooks
Merge pull request #3997 from yarikoptic/upstream-master

DOC: typos + rewording in examples/notebooks/Cell Magics.ipynb
Transform code before %prun/%%prun runs
Fix typo in ipapp
Merge pull request #4014 from sixpi/fix_matploltib_typo

Fix typo in ipapp
Add prun transform test
Merge pull request #4008 from jasongrout/prun-transform

Transform code before %prun/%%prun runs