Correct \r\n handling.
SASL: Make state implementations public.
Various formatting issues and some comments.
Handle CAP NAK and fail-abort SASL authentication in that case.
Fine-tuning
Added notes on other authentication mechanisms not currently supported.

While looking into other authentication mechanisms for IRC sasl extension,
there appear to be a number of other options available. These mechanisms
provide additional security in some kind or another. But there's still
some discussion going on about what is most reliable, so for now I'll
leave some notes only.