This is incomplete, it just adds the slots in question and assigns noops to them.
Some minor cleanup of types.
Due to the priority of the hooks, it seems we can actually coexist with module-stream restore so
the code to detect and unload it will be removed shortly.
The structure itself will contain various bits of info so exposing this fully to the client is a bad idea.
By keeping to a rename operation we keep what we do store abstracted from the clients.
Also fix some doxy comments.
This allows clients to edit the priroity order. What is not yet in place is the initialisation of that priority list
when new devices are detected or the cleaning (remove holes) when devices are removed.
In order to keep the storage transparent I will likely remove the write functionality and replace it with a
simple rename method.
I also still need to expose the priority itself when reading the data.
The routing logic itself does not yet exist, but the command currently will unload/load module-stream-restore as approriate.
(module-stream-restore would conflict with the role-based priority-routing).
This will be used as the basis for a queryable system for past and present devices, initially for use in KDE.
Currently all this module does is save lists of sinks/sources and their descriptions, so it needs to
gain a protocol extension to make this queryable.
As things stand it will save the device descriptions of all sinks and restore them if they differ from whats on record.
