Add PlayerCodeOfConductSendEvent

[mbax]

Enables customizing the code of conduct per send.

Just throwing the idea out there. Draft because I'm not sure we even want this and because I haven't bothered to test it yet (but I can't see it blowing up).

Possible uses:

1. Presently, code of conduct attempts to be based on user locale, then defaults to en_us. Perhaps someone would want to try some other locales first based on their locale.
2. Separate code of conduct for users once they're staff.
3. Separate code of conduct for visitors vs members in a "greylist" server.
4. Forcing users to always accept the code of conduct each join, or every X days, by adding a unique value to the end of the code of conduct.