Channels 3.0 - small files support

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Channels 3.0 provides the required technological foundations for adding numerous small files to existing Bittorrent videos.

A lot of our cultural heritage requires multilangual support in the form of subtitles, thumbnails for visual navigation and screen art to provide stunning backgrounds. Popular channels of libraries or vlogger collectives might require a million support files. This issue provides a single swarm to serve them all. Each 3.0 channel has a single unique hash for all support files. This hash is updated regularly and all subscribed clients incrementally seed their content.

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Should we use one swarm for channel data and small files? Possibly use the exiting swarm for Channel 2.0 for this. Extend this ORM-based design with filesystem stored binary blobs. Re-usage of the Libtorrent small file support.

[ichorid]

The problem with putting everything in a single BitTorrent swarm is described in #4677