A Processor that operates in read-only, replay-only mode, similar to a View, but can then be promoted to a normal writing Processor.
The purpose is to have a hot standby that can take over quickly without performing full recovery.
Originally discussed here: https://groups.google.com/d/msg/akka-user/EDDbRYgEKQ8/HDQBiOq36RkJ

We should evaluate if this feature is needed, or if it's too special.