Fix definition of ssize_t and off_t.

This new command triggers a config flush to save the in-memory config to
disk. This is useful for cases of a configuration management system or a
package manager wiping out your sentinel config while the process is
still running - and has not yet been restarted. It can also be useful
for scripting a backup and migrate or clone of a running sentinel.

A way for monitoring systems to check that Sentinel is technically able
to reach the quorum and failover, using the currently visible Sentinels.

uphold the smove contract to return 0 when the element is not a member of the source set, even if source=dest

Added redis.service.conf that turns on logging to the Windows event viewer. This required that we also log to a file with the logfile setting, otherwise messages are not written to the event viewer...probably a mishandling of Windows OS. The event viewer requires a messages resource in the form of a DLL, so I updated the Win32_Interop project to have a custom build step to compile EventLog.res into EventLog.dll. Updated the WiX project to create the Windows event source and also the directory where the event log file will be written.

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.

limit.

Correclty check for Windows 8 version (6.2), in case this code
path gets re-enabled again.
Note that Windows 10 has version number 10.0, so it would finally
take the code path originally intended for Windows 8 and higher.

VirtualProtect is failing with ERROR_INVALID_PARAMETER.
It's possible that this code path never worked because it is
checking for Windows version 8.0. Windows 8's version number is 6.2,
not 8.0.

Conflicts:
	src/Win32_Interop/Win32_QFork.cpp

Fix for https://github.com/MSOpenTech/redis/issues/167

RejoinCOWPages used to call QueryWorkingSetEx to figure out
which pages had been dirtied since the memory map was protected
with PAGE_WRITECOPY. But dirty pages that had been swapped out to
the system page file would be reported as not valid
(VirtualAttributes.Valid == 0) and so we wouldn't restore them into
the file map.
QueryWorkingSetEx only gives information about pages that are in the
working set at the time it is called. Pages can be forced into the
working set using VirtualLock, but that seems like a potentially
risky / expensive solution.
I implemented a solution that uses VirtualQuery to find out which
regions have changed protection from PAGE_WRITECOPY.

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.

Bug as old as Redis and blocking operations. It's hard to trigger since
only happens on instance role switch, but the results are quite bad
since an inconsistency between master and slave is created.

How to trigger the bug is a good description of the bug itself.

1. Client does "BLPOP mylist 0" in master.
2. Master is turned into slave, that replicates from New-Master.
3. Client does "LPUSH mylist foo" in New-Master.
4. New-Master propagates write to slave.
5. Slave receives the LPUSH, the blocked client get served.

Now Master "mylist" key has "foo", Slave "mylist" key is empty.

Highlights:

* At step "2" above, the client remains attached, basically escaping any
  check performed during command dispatch: read only slave, in that case.
* At step "5" the slave (that was the master), serves the blocked client
  consuming a list element, which is not consumed on the master side.

This scenario is technically likely to happen during failovers, however
since Redis Sentinel already disconnects clients using the CLIENT
command when changing the role of the instance, the bug is avoided in
Sentinel deployments.

Closes #2473.

The quasi-fork child was waiting for an explicit signal from the parent
before terminating. This synchronization step is unnecessary, and
it makes the child hang if the parent terminates for any reason
while the fork operation is in progress.
In that scenario, and consistently with the Posix version, the child
now completes the fork operation and terminates freely when done.

This fixes https://github.com/MSOpenTech/redis/issues/228

Also introducing some utility functions for translating Windows
error codes to errno error codes.
This part was adapted from existing code in libuv:
https://github.com/libuv/libuv/blob/v1.x/src/win/error.c

Itereator misuse due to analyzeLatencyForEvent() accessing the
dictionary during the iteration, without the iterator being
reclared as safe.

getpeername() is returning invalid addresses on ipv6 sockets accepted
with AcceptEx, filling only 16 bytes of the address structure.
Providing a workaround by saving the remote address returned by
GetAcceptExSockaddrs, which is valid.

The debug version of isprint() raises an assert when the input value
is not EOF or in the range 0 through 0xFF, inclusive.
The trick is that the char value needs to be passed as unsigned,
before being converted to int.

It looks like https://github.com/MSOpenTech/redis/commit/62cc0e320d9afe28cc44a642d9e8f5e1c0e5d775#diff-07ce465381b20e496c6fb51bedd3491fR3105
inadvertently made the Windows side not abort when an OOM occurs.

--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.