Instead of using a single finalized output config per output, accept a
regular list of output configs like the one ultimately stored for
configuration purposes. This allows the output management code to test
an augmented configuration while still using the same output config
logic, without having to mutate the stored configuration.
This in turn allows us to make a few APIs private. A bug note about an
existing issue with derade to off is added as well.
Kenny Levinsen