v0.x.x
  * New commands added for the Redis 2.0 (DEV) profile: 
      - Strings: APPEND, SUBSTR
      - ZSets  : ZCOUNT, ZRANK, ZUNION, ZINTER, ZREMBYRANK, ZREVRANK
      - Hashes : HSET, HINCRBY, HGET, HDEL, HEXISTS, HLEN, HKEYS, HVALS, 
                 HGETALL
      - Misc.  : DISCARD, CONFIG

  * The GET parameter for the SORT command now accepts also multiple key 
    patterns by passing an array of strings.

  * KEYS will return a multibulk reply starting from Redis 2.0 (DEV). Predis 
    handles this change in a backwards-compatible way.

  * Switched to class-based handlers instead of anonymous functions to 
    handle the various server response types.

  * CommandPipeline and MultiExecBlock return their instances when invoking 
    commands, thus allowing method chaining in pipelines and multi-exec blocks.

  * MultiExecBlock instances can handle the new DISCARD command.

  * New parameters for connections: 
      - alias [default: not set]
        every connection can now be identified by an alias that is useful to 
        get a certain connection when connected to a cluster of Redis servers.
      - weight [default: not set]
        allows the client to balance the keys asymmetrically across multiple 
        servers. This might be useful when you have servers with different 
        amounts of memory and you want to distribute the load of your keys 
        accordingly.
      - connection_async [default: FALSE]
        estabilish connections to servers in a non-blocking way, so that the 
        client is not blocked while the underlying resource performs the actual 
      - connection_persistent [default: FALSE]
        the underlying connection resource is left open when a script ends its 
        lifecycle. Persistent connections can lead to unpredictable or strange 
        behaviours, so they should be used with extreme care.

  * Connections now support float values for the connection_timeout parameter 
    to express timeouts with a microsecond resolution.

  * In addition to the classic way of fetching a whole multibulk reply into an 
    array, the client can now optionally stream a multibulk reply down to the 
    user code by using PHP iterators. It is just a little bit slower, but it 
    can save a lot of memory in certain scenarios.

  * Server errors can optionally be handled "silently": instead of throwing an 
    exception, the client returns a error response type.

v0.5.1
  * RPOPLPUSH has been changed from bulk command to inline command in Redis
    1.2.1, so ListPopLastPushHead now extends InlineCommand. The old RPOPLPUSH
    behavior is still available via the ListPopLastPushHeadBulk class so that
    you can override the server profile if you need the old (and uncorrect)
    behaviour when connecting to a Redis 1.2.0 instance.

  * Added missing support for BGREWRITEAOF for Redis >= 1.2.0

  * Implemented a factory method for the RedisServerProfile class to ease the 
    creation of new server profile instances based on a version string.

v0.5.0
  * First versioned release of Predis