A node can populate a slot if a message from a trusted slot is received claiming ownership of this slot, that is currently empty or served by a node in FAIL state. However this feature was broken since calling clusterAddSlot() was not enough as the slot bit is already set in the node that pong us. We need to directly alter the table. This commit fixes the issue.

fixes to install scripts

redisAssertWithClientInfo() is now redisAssertWithInfo() that is also able to report an optional object. The client is also optional. Specifying NULL will prevent dumping the not available information (either client or object).

Introduced a redisAssert() variant that is able to show information about the client in the context where the failed assertion was detected.

redis-trib: create subcommand fixed calling node info loading method. Was needed after recent refactoring.

Redis test ports selection made more robust. This prevents the test from hanging if an already bound port is selected but the TCP server listening to it does not cause a protocol error with a Redis client PING. Also base port moved away from the range near to the Redis Cluster gossip ports.

Revert "Use the new install script as make install target. Message about install script requiring root changed a bit to make it more evident."
After talking with Pieter he changed my mind about this, it is better to
have a simpler install script that works everywhere, and the complex one
can be always executed if needed by hand. We'll make possibly a new
target for the full featured installation script, and even suggest it
after a Make install.

This reverts commit f1e60d75.

Rewrite MIGRATE as DEL for AOF/replication. Also increment the dirty counter to both force replication and persistence.

increment server.dirty in restore command to make sure it is replicated and increments the dirty count for persistence concerns.

Use rank information to compute ZCOUNT

Use the new install script as make install target. Message about install script requiring root changed a bit to make it more evident.

when processing gossip packets make sure to also update the node bitmap when associating slots to nodes. Fixed simply using the appropriate helper function to add a slot.

redis-trib: initial working implementation of cluster rehashing, more work needed to make it more correct, more reliable.

Clear the importing status from the slot if a CLUSTER SETSLOT command permanently assigns the slot to the importing node.

redis-trib: initial slots allocation strategy, still to improve for better balancing when there are just a few slots to move.

redis-trib: minor refactoring creating a method to load the cluster information starting from a single node

Fixed command table for RESTORE to make it accepting keys only for the right slots when cluster is enabled.