• Switch to C++17
• New stuff
• Method agent_t::so_make_new_direct_mbox()
• New class message_holder_t for working with preallocated or stored messages.
• Changed stuff
• Cooperations of agents
• Only one kind of dispatchers
• Format of event-handlers
• Helpers introduce_coop()/introduce_child_coop() now return values
• Now every mbox has a reference to SOEnv. New formats of send_delayed()/send_periodic()
• receive() and select() functions now require handle_all()/handle_n()/extract_n() restriction
• abstract_message_box_t interface changed
• Removed stuff
• Synchronous interaction between agents
• One of event-handler formats
• Ad-hoc agents
• Some methods which accept raw pointers
• Typedef event_data_t
• Simple forms or receive() and select() functions
• Methods schedule_timer() and single_timer() from environment_t
• Old send-family functions like send_to_agent()
• No more so_make_state() method
• No more tuple_as_message
• Namespace so_5::rt
• Various deprecated stuff removed