Default implementation of :communication_module.

This is introduced in order to work-around slow message passing to unreachable nodes. In other words, it uses a temporary process to send message to a not-yet-connected node, as in the same way as :gen_server.cast/2.

Essentially send_event/2 behaves as :gen_statem.cast/2 and reply/2 behaves as :gen_statem.reply/2. The discrepancy in the name of send_event comes from a historical reason (:gen_fsm had been used).