Message oriented BASP

The application layer in the current design is message-oriented, while `BASP` is stream-oriented. We should think about reworking the current stream-oriented design to be message oriented, so that the underlying communication model stays
consistent.
An easy way to do so would be an adaptor that is situated directly on top of the transport abstraction. This adaptor could process the received data and create a message that is passed on further up the stack. This way, working with datagrams is less of a problem, while this change would not affect stream and message oriented transport protocols.

What do you think about this idea @Neverlord ?