Authors fixup

Fix spelling errors in AUTHORS (caught by ispell), and add more people to AUTHORS

I've added everyone from https://github.com/barnowl/barnowl/graphs/contributors whose name I knew (or whose name was listed on their profile page).  I did not manage to list austein, ecprice, or timhillgit.  I guessed that rileyb is rileyb@mit.edu, and used MIT people search to guess "Amy Riley".