Related to issue #2306.

Related to issue #2306.

--stat mode already used to reconnect automatically if the server is no
longer available. This is useful since this is an interactive mode used
for debugging, however the same applies to --latency and --latency-dist
modes, so now both use the reconnecting command execution as well.

The reconnection code was modified to use basic VT100 escape sequences
in order to play better with different kinds of output on the screen
when the reconnection happens, and to hide the reconnection attempt
output when finally the reconnection happens.

So far not able to find a color palette within the 256 colors which is
not confusing. However I believe it is a possible task, so will try
better later.

Still not happy with the result but low grays are hard to see in certain
monitors with a non perfect gamma.

This test on Linux was extremely slow, since in Tcl we can't enable
easily tcp-nodelay, so the busy loop used to take *a lot* with bigger
writes. Fixed using pipelining.

Code was adding '\n'  (line 521) to the end of NIL values exlusively making csv output inconsistent.  Removed '\n'

This improves PFAIL -> FAIL switch. Too late at this point in the RC
releases to add proper PFAIL/FAIL separate dictionary to do this in a
less randomized way. Tested in practice with experiments that this
helps. PFAIL -> FAIL average with 20 nodes and node-timeout set to 5
seconds takes 2.5 seconds without this commit, 1 second with this
commit.

Otherwise we risk sending not initialized data to other nodes, that may
contain anything. This was actually not possible only because the
initialization of the buffer where the cluster packets header is created
was larger than the 3 gossip sections we use, so the memory was already
all filled with zeroes by the memset().

Otherwise we risk sending not initialized data to other nodes, that may
contain anything. This was actually not possible only because the
initialization of the buffer where the cluster packets header is created
was larger than the 3 gossip sections we use, so the memory was already
all filled with zeroes by the memset().

Otherwise it is impossible to receive the majority of failure reports in
the node_timeout*2 window in larger clusters.

Still with a 200 nodes cluster, 20 gossip sections are a very reasonable
amount of bytes to send.

A side effect of this change is also fater cluster nodes joins for large
clusters, because the cluster layout makes less time to propagate.

Simple shell script to create / destroy Redis clusters for manual
testing.

Removes some percentage of timing related failures.

On Darwin /dev/urandom depletes terribly fast. This is not an issue
normally, but with Redis Cluster we generate a lot of unique IDs, for
example during nodes handshakes. Our IDs need just to be unique without
other strong crypto requirements, so this commit turns the function into
something that gets a 20 bytes seed from /dev/urandom, and produces the
rest of the output just using SHA1 in counter mode.

Otherwise between the two commands other nodes may contact us making the
next SET-CONFIG-EPOCH call impossible.

Fixes valgrind error:
48 bytes in 1 blocks are definitely lost in loss record 196 of 373
   at 0x4910D3: je_malloc (jemalloc.c:944)
   by 0x42807D: zmalloc (zmalloc.c:125)
   by 0x41FA0D: dictGetIterator (dict.c:543)
   by 0x41FA48: dictGetSafeIterator (dict.c:555)
   by 0x459B73: clusterHandleSlaveMigration (cluster.c:2776)
   by 0x45BF27: clusterCron (cluster.c:3123)
   by 0x423344: serverCron (redis.c:1239)
   by 0x41D6CD: aeProcessEvents (ae.c:311)
   by 0x41D8EA: aeMain (ae.c:455)
   by 0x41A84B: main (redis.c:3832)

If array has N elements, we can't read +1 if we are already at N.

Also, we need to move elements by their storage size in the array,
not just by individual bytes.

[maybe] Fixes valgrind errors:
32 bytes in 4 blocks are definitely lost in loss record 107 of 228
   at 0x80EA447: je_malloc (jemalloc.c:944)
   by 0x806E59C: zrealloc (zmalloc.c:125)
   by 0x80A9AFC: clusterSetMaster (cluster.c:801)
   by 0x80AEDC9: clusterCommand (cluster.c:3994)
   by 0x80682A5: call (redis.c:2049)
   by 0x8068A20: processCommand (redis.c:2309)
   by 0x8076497: processInputBuffer (networking.c:1143)
   by 0x8073BAF: readQueryFromClient (networking.c:1208)
   by 0x8060E98: aeProcessEvents (ae.c:412)
   by 0x806123B: aeMain (ae.c:455)
   by 0x806C3DB: main (redis.c:3832)

64 bytes in 8 blocks are definitely lost in loss record 143 of 228
   at 0x80EA447: je_malloc (jemalloc.c:944)
   by 0x806E59C: zrealloc (zmalloc.c:125)
   by 0x80AAB40: clusterProcessPacket (cluster.c:801)
   by 0x80A847F: clusterReadHandler (cluster.c:1975)
   by 0x30000FF: ???

80 bytes in 10 blocks are definitely lost in loss record 148 of 228
   at 0x80EA447: je_malloc (jemalloc.c:944)
   by 0x806E59C: zrealloc (zmalloc.c:125)
   by 0x80AAB40: clusterProcessPacket (cluster.c:801)
   by 0x80A847F: clusterReadHandler (cluster.c:1975)
   by 0x2FFFFFF: ???