Introduce Rc owned management structs

[elfenpiff]

Brief feature description

Currently, it is impossible to store a service with its corresponding ports and corresponding samples in a cache inside one struct due to the problems of Rust self referencing structs.

So something like:

struct MyThing {
  service: Box<dyn Service<MessageType>>,
  subscriber: Box<dyn Subscribe<MessageType>>,
  sample_cache: Vec<Box<dyn Payload<MessageType>>>,
}

cannot be realized. Every sample in the sample_cache holds a reference to the subscriber to release itself when going out of scope. Also, the subscriber holds a reference to service to remove it from the service when it goes out of scope.

The solution is, that the underlying construct, that performs the task, is stored in an Rc and has a shared ownership. When this is done, the lifetime restrictions should be lifted.

Introduce Rc and lift lifetime restrictions

• Config
• Sample
• SampleMut
• Publisher
• Subscriber
• Notifier
• Listener
• Remove needless traits Notify, Listen, Publish, Subscribe, Payload, PayloadMut & Update changelog