Previously, the associated types on `NetworkBehaviour` and `ConnectionHandler` carried generic names like `InEvent` and `OutEvent`. These names are _correct_ in that `OutEvent`s are passed out and `InEvent`s are passed in but they don't help users understand how these types are used.
In theory, a `ConnectionHandler` could be used separately from `NetworkBehaviour`s but that is highly unlikely. Thus, we rename these associated types to indicate, where the message is going to be sent to:
- `NetworkBehaviour::OutEvent` is renamed to `ToSwarm`: It describes the message(s) a `NetworkBehaviour` can emit to the `Swarm`. The user is going to receive those in `SwarmEvent::Behaviour`.
- `ConnectionHandler::InEvent` is renamed to `FromBehaviour`: It describes the message(s) a `ConnectionHandler` can receive from its behaviour via `ConnectionHandler::on_swarm_event`. The `NetworkBehaviour` can send it via the `ToSwarm::NotifyHandler` command.
- `ConnectionHandler::OutEvent` is renamed to `ToBehaviour`: It describes the message(s) a `ConnectionHandler` can send back to the behaviour via the now also renamed `ConnectionHandlerEvent::NotifyBehaviour` (previously `ConnectionHandlerEvent::Custom`)
Resolves: #2854.
Pull-Request: #3848.
Currently, our top-level `Cargo.toml` manifest represents a crate AND a workspace. This causes surprising behaviour (e.g. #2949) where we need to explicitly pass `--workpace` to every command to run it on the entire workspace and not just the meta crate.
My moving the meta crate into its own directory, the root manifest file is a virtual manifest only and thus, every `cargo` command will automatically default to running on the entire workspace.
On top of this, I personally find it easier to understand if workspace and crate manifests are not mixed.
Pull-Request: #3536.
