Cluster: from 4096 to 16384 hash slots.
Cluster: redis-trib updated to use 16384 hash slots.
Cluster: Initialize ip and port in createClusterNode().
Cluster: the cluster state structure is now heap allocated.
Cluster: move cluster config file out of config state.

This makes us able to avoid allocating the cluster state structure if
cluster is not enabled, but still we can handle the configuration
directive that sets the cluster config filename.
Cluster: with 16384 slots we need bigger buffers.