[Implemented] Canceling SOS call

[Towcat]

i don't complain about "civilians" helping each other, but really annoying are those people, who arrive at the towing scene, when i'm already doing my job there, and start blind ramming into the flipped car.
i try to help too, no matter what car i got under my ass... except uf1 maybe

well if someone arrives before i do and i see... ok that doesn't seem to work how he's doing it... i ask the person to let me try it.

savy, you say medics only stand next to flipped cars, being proud to be allowed to use a siren?
for some time now i wear a medic tag instead of a tow tag... but i don't really act different. i'm not even excessively speeding with sirens to my target.

well to get back to the point... i support the idea of a cancel BUTTON, not a command (people will click the button to get rid of it, but they are too lazy to type a command)