Identify users. Optional auth

[euank]

Users should be identified by their nickserv login probably. possibly optional auth to allow a user to login to the bot directly without any regard to nickserv.

The identify module should allow a way to look up a "canonical" id for a user.

[euank]

Additional ideas:

Three types of accounts: Weak Inferred, Nickserv, Manually created

1. Weak Inferred: Inferred based on login host, nick, watching nickchanges, and so on. This is easy to spoof.
2. Nickserv - Based on nickserv account, not spoofable.
3. Manually created - You messaged the bot and explicitly created a username/password to auth with it. You must login directly with the bot.

Each account gets a UUID. A user may at any time upgrade an account and keep UUID (e.g. register for nickserv and upgrade, register for manual account and upgrade) but never downgrade.

The account module should be able to return a UUID based on nick.