ZeroNet as a platform for overlay networks.

Can ZeroNet be used as a library to create an overlay network of nodes interested in topic `foo/1.2.3` and let them exchange with arbitrary messages? Number of nodes: ~1M. Message size: < 1 KB.

For example, I want to make a distributed p2p version of a books catalogue. Ther catalogue has a well-known name, e.g. `books/1.2.3`. Nodes use this name to discover other nodes connected to this overlay network. Once connected, they download the list of book ids from a peer. If someone wants to add a book, they send its id to a few peers, they add it to the local storage and re-transmit to other peers. An important property of this system is that all the nodes are equal: there is no admin who has special rights. There is no special private key that has special rights in this catalogue.

API needed for this:
- `join("books/1.2.3")` finds a few peers in this overlay network
- `peers("books/1.2.3")` returns the list of online peers we're currently connected to
- `send("books/1.2.3", peerId, "howdy")` sends a message to the given peer
- `listen("books/1.2.3", callback)` gets messages sent by other peers with the `send()` API

Thoughts?

L’issue n’identifie ni fichiers, ni tests, ni point d’entrée pour l’implémentation. Déterminez d’abord si ZeroNet prend en charge le modèle de réseau overlay et l’API proposés, puis définissez l’architecture et les critères d’acceptation pour la découverte des pairs, la messagerie, le stockage et des permissions équivalentes pour les nœuds.

Rédigé par le modèle d'indexation à partir du texte de l'issue.