created events folder and moved base event to it
created events test folder
generated ExitEvent class
added exit() function to simulation class
added get_state() function to simulation class
updated process_event() to process_event(void*)
added methods to bind a parent object to EventManager class
added code comments
EventManager now passes ref for parent object into each process_event() call
implemented exit event
simulation now waits for exit event if no duration is set
Merge branch 'create-exit-event' into development