Client creates a string "1 2 3 ... 10000 ...", sends it to the server
along with the maximum number in the string.
Server creates another string like the client sent.
It validates it and, returns strcmp()'s result.
This is loop-ed every 2 seconds.
rename the ADD_WATCH/REMOVE_WATCH messages to SUBSCRIBE/UNSUBSCRIBE and change
the message format and libubus API in preparation for adding object notifications
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
