remove deferred reads

Ok, I'd like to apply this patch:
http://www.squid-cache.org/~robertc/deferred.patch.bz2
asap (Adrian has a couple of comms things to work on that depend on this
to prevent collisions).

It
* removes deferred reads across the board
* converts nearly all unready reads to the new DeferredRead framework.
* leaves ssl reading 1 byte per IO cycle at minimum.
* Includes David Nicklay's epoll patch.

This should allow kqueue and epoll to properly support delay pools.

Cheers,
Rob

-- 
GPG key available at: <http://users.bigpond.net.au/robertc/keys.txt>.