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