fix compile error for struct msghdr in FreeBSD 10

Probably this stuff should be called CLIENT_* in order to cross merge
more easily.

fix sds.c

update copyright year

Originally, only the +slave event which occurs when a slave is
reconfigured during sentinelResetMasterAndChangeAddress triggers a flush
of the config to disk.  However, newly discovered slaves don't
apparently trigger this flush but do trigger the +slave event issuance.

So if you start up a sentinel, add a master, then add a slave to the
master (as a way to reproduce it) you'll see the +slave event issued,
but the sentinel config won't be updated with the known-slave entry.

This change makes sentinel do the flush of the config if a new slave is
deteted in sentinelRefreshInstanceInfo.

To rewrite the config in the loop that adds slaves back after a master
reset, in order to handle switching to another master, is useless: it
just adds latency since there is an fsync call in the inner loop,
without providing any additional guarantee, but the contrary, since if
after the first loop iteration the server crashes we end with just a
single slave entry losing all the other informations.

It is wiser to rewrite the config at the end when the full new
state is configured.

Fix Redis server crash when Lua command exceeds client output buffer limit.

fix sentinel memory leak

As suggested in #2543.

Fix spelling and grammatical errors in readme

This fixes issue #2535, that was actually an hiredis library bug (I
submitted an issue and fix to the redis/hiredis repo as well).

When an asynchronous hiredis connection subscribes to a Pub/Sub channel
and gets an error, and in other related conditions, the function
redisProcessCallbacks() enters a code path where the link is
disconnected, however the function returns before freeing the allocated
reply object. This causes a memory leak. The memory leak was trivial to
trigger in Redis Sentinel, which uses hiredis, every time we tried to
subscribe to an instance that required a password, in case the Sentinel
was configured either with the wrong password or without password at
all. In this case, the -AUTH error caused the leaking code path to be
executed.

It was verified with Valgrind that after this change the leak no longer
happens in Sentinel with a misconfigured authentication password.

Closes #2549

An user changed the behavior via a PR without upgrading the doc.

limit.

Added reference to IANA ticket for port 6379

Just so it's extra official 😄

When we fail to setup the write handler it does not make sense to take
the client around, it is missing writes: whatever is a client or a slave
anyway the connection should terminated ASAP.

Moreover what the function does exactly with its return value, and in
which case the write handler is installed on the socket, was not clear,
so the functions comment are improved to make the goals of the function
more obvious.

Also related to #2485.

fixes to diskless replication.

This should likely fix a false positive when running with the --valgrind
option.

master was closing the connection if the RDB transfer took long time.
and also sent PINGs to the slave before it got the initial ACK, in which case the slave wouldn't be able to find the EOF marker.

Segfault introduced during a refactoring / warning suppression a few
commits away. This particular call assumed that it is safe to pass NULL
to the object pointer argument when we are sure the set has a given
encoding. This can't be assumed and is now guaranteed to segfault
because of the new API of setTypeNext().

This change fixes several warnings compiling at -O3 level with GCC
4.8.2, and at the same time, in case of misuse of the API, we have the
pointer initialize to NULL or the integer initialized to the value
-123456789 which is easy to spot by naked eye.

Another one just to avoid a warning. Slightly more defensive code
anyway.

Change done in order to remove a warning and improve code robustness. No
actual bug here.

No semantical changes since to make dict.c truly able to scale over the
32 bit table size limit, the hash function shoulds and other internals
related to hash function output should be 64 bit ready.