Support for group commands ("All off") from Intertechno controls

[databus23]

I noticed that the "All off" command of my ITT-1500 Intertechno remote does not seem to be supported by rcpulsegw. When I push the "All off" button on any my ITT-1500 controls it shows up in mqtt as an "off" command for the 1 channel:

# off button pressed for first channel
home/rcpulse/intertechno/13961122/1 OFF
home/rcpulse/hama/13961122/16 OFF

# "All off" button pressed
home/rcpulse/intertechno/13961122/1 OFF
home/rcpulse/hama/13961122/16 OFF

This results in constant state inconsistencies in home-assistant as off commands for the other channels are not recorded then using the "All off" command.

I tried to look into adding support for it myself but I have to admit I don't understand the intricacies of rcprotocols.py and how to modify or debug it. Also trying to debug what data is actually send over the air its not obvious to me how to map the "raw" output of rcpulse to anything that resamples the 32bit commands that make up the PPM 32 Bit protocol explained here

Any pointers in how to add support for group command for the protocol would be appreciated.