Remove WP Dependencies

call the protected method cause it exists

added authentication to connect with Redis

I have to use authentication to connect with Redis. (hosting is using PHPRedis instead of PRedis)

Fully working implementation

Ensure that data retrieved in a `get_multi()` request is properly restored to the original data type.

See bd44ddf5.

Fixes #5.

Fixes #4

See #4

* Catches connection exceptions rather than triggering fatals
* Forces all cache lookups to use the internal cache when Redis is unavailable

Fixes #1

Add method for changing the blog-specific cache prefix when switching blogs in a multisite environment.

Add handling for the various responses Predis returns after performing an action, ensuring a boolean always results.

Remove `wp_cache_increment()` and `wp_cache_decrement()` as they aren't part of Core's implementation.

Users switching between cache backends shouldn't have to worry about function names changing. That's not how Core's object cache is designed.

Implement `increment()` and `decrement()` methods for the corresponding `wp_cache_incr()` and `wp_cache_decr()` functions.

Remove methods held over from original Memcache plugin, but that aren't part of Core's object cache implementation.

While some do have equivalents in Redis, others don't. For now, aim for something streamlined and the extras can come later.

Remove irrelevant arguments related to multiple servers (holdover from Memcache basis) and update PHPDoc accordingly.

Correct order of arguments passed to `setex()` as they were incorrect--the expiration and value to cache were inverted.

Bug has existed since baa6de52 but was masked by serialization bug fixed in 01b7283c.

Also fixes a code error introduced in 01b7283c, where the key, not the retrieved value, was passed to the `restore_value_from_redis()` method.

Correct error in how additional global and non-persistent groups are added, which corrupted the arrays holding those groups.

In 868c0a8c, I blindly copied two missing functions from another object caching plugin, not paying enough attention to how that plugin managed the data versus how this plugin does. As a result, the arrays of groups had some entries keyed by the group, others were unkeyed and the value represented the group.