lazyfree: fix memory leak for lazyfree-lazy-server-del

redis-benchmark: bugfix - handle zero liveclients in right way

Added RM_UnlinkKey - a low level analog to UNLINK command

Fix a typo(maybe instruction?) in crash log

This fixes a crash with Redis Cluster when OBJECT is mis-used, because
getKeysUsingCommandTable() will call serverPanic() detecting we are
accessing an invalid argument in the case "OBJECT foo" is called.

This bug was introduced when OBJECT HELP was introduced, because the key
argument is set fixed at index 2 in the command table, however now
OBJECT may be called with an insufficient number of arguments to extract
the key.

The "Right Thing" would be to have a specific function to extract keys
from the OBJECT command, however this is kinda of an overkill, so I
preferred to make getKeysUsingCommandTable() more robust and just return
no keys when it's not possible to honor the command table, because new
commands are often added and also there are a number with an HELP
subcommand violating the normal form, and crashing for this trivial
reason or having many command-specific key extraction functions is not
great.

We already had client buffer limits exported as configuration options.
Stick with the naming scheme already used.

See #4568.

Related to #4568.

fix RESTORE command size limits

Fix the firstkey, lastkey, and keystep of moduleCommand

Related to #2507.

See PR #2507. This is a reimplementation of the fix that contained
different problems.

Fix memory usage list bug

- protocol parsing (processMultibulkBuffer) was limitted to 32big positions in the buffer
  readQueryFromClient potential overflow
- rioWriteBulkCount used int, although rioWriteBulkString gave it size_t
- several places in sds.c that used int for string length or index.
- bugfix in RM_SaveAuxField (return was 1 or -1 and not length)
- RM_SaveStringBuffer was limitted to 32bit length

This is a fix for the #3819 improvements. The o->ptr may change because
of hllSparseSet() calls, so 'hdr' must be correctly re-fetched.

This is a fix for #3819.

The commit splits the add functions into a set() and add() set of
functions, so that it's possible to set registers in an independent way
just having the index and count.

Related to #3819, otherwise a fix is not possible.

fixbug for #4538 Error opening /setting AOF rewrite IPC pipes: No suc…

Always enable command history in redis-cli run on a TTY

Prevent off-by-one read in stringmatchlen()

Related to #4498.

Aof safe write -- fix the short write

- when redis-cli is running in a TTY - always enable command history
buffering, regardless if history file path can be successfully
determined

Fix #3665.

The main change introduced by this commit is pretending that help
arrays are more text than code, thus indenting them at level 0. This
improves readability, and is an old practice when defining arrays of
C strings describing text.

Additionally a few useless return statements are removed, and the HELP
subcommand capitalized when printed to the user.

We have this operation in two places: when caching the master and
when linking a new client after the client creation. By having an API
for this we avoid incurring in errors when modifying one of the two
places forgetting the other. The function is also a good place where to
document why we cache the linked list node.

Related to #4497 and #4210.

networking: optimize unlinkClient() in freeClient()