tutorial: fix grammar, spelling, punctuation I restrained myself to making only changes that turn bad English into good English. There are still opportunities to improve the tutorial, but other changes require some discussion and review. This change should be uncontroversial. The same changes had to be duplicated in both copies of the tutorial (hmmm); it's not clear which one is definitive.

syntax: re
/figures/[^/]+\.png$
^docs/build/
^docs/html/
^html/
\.pyc$
~$
\.swp$
\.orig$
\.rej$
\.err$
^tests/easy_run.sh$
^build/
^MANIFEST$
^docs/tutorials/.*\.rst$
\.ico$