Ignore more generated files.

git-svn-id: svn+userv://snowball.tartarus.org/snowball/trunk/pystemmer@572 633ccae0-01f4-0310-8c99-d3591da6f01f
Add an AUTHORS file for PyStemmer

git-svn-id: svn+userv://snowball.tartarus.org/snowball/trunk/pystemmer@573 633ccae0-01f4-0310-8c99-d3591da6f01f