Fix for issue 516, rewriting the command vector to correctly repliate BRPOPLPUSH. Still to test everything, especially edge cases

Fix for Pub/Sub system, introduced in Redis 2.2.6 with the new copy-on-write safe iterator semantics. In the hope this is the last bug I introduced this way.

removed assert causing an illegal memory access. This was responsible of crashes during BLPOP and other list blocking operations.

Introduced a safe iterator interface that can be used to iterate while accessing the dictionary at the same time. Now the default interface is consireded unsafe and should be used only with dictNext()

when Redis fails accepting a new connection reports the error at WARNING and not VERBOSE error level. Thanks to offby1 for proposing this in the Redis mailing list. #backport-candidate

Fixed a bug with replication where SLAVEOF NO ONE caused a slave to close the connection with its slaves

This reverts commit 1b905277.
Moving all the new stuff in 2.4 branch.

This reverts commit c138dc7d.
Moving all the new stuff in 2.4 branch.

make sure that OBJECT ENCODING returns skiplist for sorted sets, and not raw, so that once we will merge specially encoded sorted sets everything will make sense.

fixed memory leak introduced with the previous commit. Many thanks to Pieter Noordhuis for spotting it in no time