Feed control system

[eagle]

This is something that's been bouncing around for a long time, and there are various external systems such as GUP that have shown up. It may not need to be something integrated with INN, but it would be a nice problem to solve.

Some thoughts from Kai Henningsen:

1. Each (downstream) peer has up to N subfeeds that can be configured pretty much independently, corresponding to entries in newsfeeds

2. For each subfeed, there's an uwildmat [list] and possibly other attributes

3. Each peer can (by some transport) set, get, and modify a request for any of its N subfeeds detailing these attributes

4. These requests, together with local downstream and upstream peer configs, get munged by admin scripts (applying whatever policy is wanted) to produce (a) "real" requests (newsfeeds entries) or (b) outgoing requests for upstream peers peers (to be transmitted by whatever transport). This step probably needs reasonable docs on how to make sure your peers don't overload you with binaries, and so on, and any default should be set up that way. And it would probably be useful to have a needs-manual-confirmation mode here.

Local policy would decide when 4a and 4b happen - not necessarily at the same time.