Is there any way the alarm plugins could "save" one alarm time in the sb2
itself, to avoid not triggering it at all when the slimserver / connection to
sqn goes down?

It'd go something like this:

1. User modifies alarm settings
2. If any alarms are active start a timer on the sb2 itself that runs to 1-2
   seconds after the time of the next active alarm.
3. If everything is still fine (server up, etc) when the alarm should trigger,
   do as we do now, clear the sb2 internal alarm (and set the next active one,
   if any)
4. If the sb2's internal alarm does trigger that means something is wrong with
   the server connection. BEEP loudly, annoyingly and continously so people wake
   up. Display corresponding message.

One problem: The flash chip probably wasn't made for this, so there is no
persistent storage. This in turn means that we lose the internal timer after a
power outage. Proposed solution: If the sb2 does not manage to connect with its
stored config, i. e. slimserver is (still) down, BEEP. If there is no stored
config, BEEP.

That way the alarm should be triggered at the right time whenever possible, and
the user be alerted whenever there's the possibility of an alarm lost.