Logging in and creating new accounts using Twitch has been disabled for the foreseeable future. The feature has many problems with it and isn't used that often, so it's not worth the time it'll take to get it working 100% right.
This update also allowed me to improve the current login & registration. That means that you should stay logged in quite a bit longer now (forever), unless you clear your browser's information.
If you had an account that used Twitch to login with, please send me an email at
email@example.com with your username and a password you would like added to your account.