Matrix login input should accept @librem.one email address

Librem One is designed for people to have a single login / password to connect to all services. The login is a convenient universal ID, in the form of a @librem.one email address that should be accepted by all Librem One services for connecting.

Therefore, Chatty should automatically detect an email identifier within the login input and translate it to the much less common Matrix identifier.

username@librem.one => @username:librem.one