nd a new event and return an updated list of events.
 
  BTKAPPENDEVENT(H, LABEL, TIME, CONTEXT) append an event with the label LABEL,
  the time TIME and the context CONTEXT.  Even if there is no rule for the context,
  these 3 contexts are oftenly used: General, Left, Right.  Moreover, as an event is
  defined by also a subject, description and id and they are not provided by this 
  function, they are automaticaly set.  If the metadata exists, the first value
  in the metadata SUBJECTS:NAMES is used to s