implement simple alarm via chat

[markus2330]

Alarm messages sent to NC should be read as alarm commands of other devices participating in this chat.

E.g. with devices A,B,C, device A sends: 🚨 Feueralarm! Feueralarm! FEUERALARM! ⏰. {} and additionally \alarm fire, the devices B and C receive this as command to also execute the (fire) alarm (bell or audio bell).

(A would also get back its command but as it is already in fire mode, it would ignore it.)