Detect SSL 2.0 clients and reject them
Add IPv6 support
Make server stoppable with interrupt

Allows the server to be terminated from the client handler.
self.server.shutdown() cannot be called because it waits indefinitely
on itself.
README: ftps on curl and KIO have been tested
SMTP support
IMAP support
POP3 support
README: add smtp, imap, pop3 to supported list