Renamed Session class to RealSession.
Renamed TestSession unit.
Startet implementing the SocketSession class
More space in diagram.
SocketSession calls async_read when it starts to listen.
Plans for how the protocol should be and be implemented
Added read_payload member function for prot::File
FileHandle is now a Deliverable.
A File can now act upon an Executor.
Added NotAcknowledged class.
prot::File returns NotAcknowledged when failing to open file.