Instead, connection and digipeater now update a event code passed by reference
to the maintain() function. This was the only place where the callback was
called before.
Minor side effect: maintain must be called multiple times if multiple events
trigger at the same time.
This prevents loss of precision that occurs with double-precision floats if
timestamps become very large. Timestamps are already large if they contain a
UNIX time value (requires 60 bits; double has 53 bit resolution).
Thomas Kolb