PHP extension for interfacing with Redis

This extension provides an API for communicating with Redis servers.

phpredis 4.0.0RC2

*** WARNING! THIS RELEASE CONTAINS BRAKING API CHANGES! ***

* Add proper ARGINFO for all methods. (Pavlo Yatsukhnenko, Michael Grunder)
* Let EXISTS take multiple keys [cccc39] (Michael Grunder)
* Use zend_string as returning value for ra_extract_key and ra_call_extractor [9cd05911] (Pavlo Yatsukhnenko)
* Implement SWAPDB and UNLINK commands [84f1f28b, 9e65c429] (Michael Grunder)
* Return real connection error as exception [5b9c0c60] (Pavlo Yatsukhnenko, Michael Grunder)
* Disallow using empty string as session name. [485db46f] (Pavlo Yatsukhnenko)
* Use zend_string for storing auth and prefix members [4b8336f7] (Pavlo Yatsukhnenko)
* The element of z_seeds may be a reference on php7 [367bc6aa, 1e63717a] (@janic716)
* Avoid connection in helper methods [91e9cfe1] (Pavlo Yatsukhnenko)
* Add tcp_keepalive option to redis sock [68c58513, 5101172a, 010336d5, 51e48729] (@git-hulk, Michael Grunder)
* More robust GEORADIUS COUNT validation [f7edee5d] (Michael Grunder)
* Add LZF compression (experimental) [e2c51251, 8cb2d5bd, 8657557] (Pavlo Yatsukhnenko)
* Allow to use empty string as persistant_id [ec4fd1bd] (Pavlo Yatsukhnenko)
* Don't use convert_to_string in redis_hmget_cmd [99335d6] (Pavlo Yatsukhnenko)
* Allow mixing MULTI and PIPELINE modes (experimental) [5874b0] (Pavlo Yatsukhnenko)
* PHP >=7.3.0 uses zend_string to store `php_url` elements [b566fb44] (@fmk)
* Documentation improvements (Michael Grunder, @TomA-R)