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.

Serialize data when necessary as Redis only accepts strings. Also, properly store non-expiring values.

Supports alternative Redis configurations without requiring hacks to the plugin file

Prevent redeclaration fatals when the object cache class is instantiated more than once, as happens with Batcache.

The `WP_Object_Class` implementation already leverages the data these two methods manipulate.

Update README.md

tiny correction in code

added an alternative connection to Redis. Copied this information from https://raw.github.com/nrk/predis/v0.8/README.md