Instead of calling redisPanic() to abort the server.

Related to issue #2302.

Related to issue #2302.

The cleanup code expects that if 'di' is not NULL, it is a valid
iterator that should be freed.

The result of this bug was a crash of the AOF rewriting process if an
error occurred after the DBs data are written and the iterator is no
longer valid.

This fix is from @NanXiao, however I was not able to retain authorship
because the Pull Request original repository was removed.

1. Server unxtime may remain not updated while loading AOF, so ETA is
not updated correctly.

2. Number of processed byte was not initialized.

3. Possible division by zero condition (likely cause of issue #1932).

Fixes issue #2225.

Otherwise there are security risks, especially when providing Redis as a
service, the user may "sniff" for admin commands renamed to an
unguessable string via rename-command in redis.conf.

The old list did not made much sense... and the flag is currently not
used at all, so no side effects.

Adds a symlink for redis-sentinel when Make install

It fixes a bad bug that crashes the server in certain conditions
as shown in issue #2210.

Related to #2094.

People mostly use SORT against lists, but our prior
behavior was pretending lists were an unordered bag
requiring a forced-sort when no sort was requested.

We can just use the native list ordering to ensure
consistency across replicaion and scripting calls.

Closes #2079
Closes #545 (again)

status command currently reports success when redis has crashed and the pid file still exists. Changing to check the actual process is running.

Improved getting pid

See https://sourceware.org/glibc/wiki/Release/2.20#Packaging_Changes

```sh
$ ~ pidof redis-server
# nothing

$ ~ ps aux | grep [r]edis
redis      593  0.0  0.0  36900  5564 ?        Ssl  Dec02   1:37 /usr/bin/redis-server 127.0.0.1:6379
klay     15927  0.0  0.0  16772  6068 pts/6    S+   13:58   0:00 redis-cli

$ ~ uname -a
Linux edge 3.17.4-1-ARCH #1 SMP PREEMPT Fri Nov 21 21:14:42 CET 2014 x86_64 GNU/Linux
```

This allows shell pipes to correctly end redis-cli.

Ref #2066

Thanks to @badboy for the help in checking the build after the fix.

Track bandwidth used by clients and replication (but diskless
replication is not tracked since the actual transfer happens in the
child process).

This includes a refactoring that makes tracking new instantaneous
metrics simpler.