[timed] Trigger recurring events missed by <59 secs during startup

When a recurring event is loaded, then set the flag trigger_if_missed (see machine.cpp 778-779). Then, when calculating the next recurrence for the event, check if timed has been running for less than 59 seconds. If that is the case, and the flag trigger_if_missed is set, then calculate the next trigger time as if the event should go off 59 seconds - current running time in the past.

When an alarm with the trigger_if_missed flag is triggered, then the flag is set to false in state_triggered_t::enter(..).