The "ready to write" notifier we set up in generic socket connection is
really only meant to detect a successful connection. Once we have a TCP
connection, for example, it will fire on every event loop iteration.
This was causing IRC Client to max out the CPU by getting this no-op
notifier callback over and over.
Since this was only used by TLSv12, I changed that code to create its
own notifier instead. It might be possible to improve TLS performance
by only processing writes when actually needed, but I didn't look very
closely at that for this patch. :^)
Contrary to popular belief, not every implementation of TLS follows the
specs.
Some of them just drop the connection without sending a proper
close_notify, and we should handle that gracefully.
