sendTrig in id value

On receiving a trigger (0 to non-zero transition), send a trigger
message from the server back to all registered clients.  Clients
register by sending a /notify message to the server.

input - the trigger

id    - an integer that will be passed with the trigger message.  This
  	is useful if you have more than one SendTrig in a SynthDef

value - a UGen or float that will be polled at the time of trigger,
        and its value passed with the trigger message

> withSC3 (\fd -> do send fd (notify True)
>                    wait fd "/done")

> s <- lfNoise0 KR 10
> audition (MRG [sendTrig s 0 s, out 0 (sinOsc AR (s * 200 + 500) 0 * 0.1)])

> withSC3 (\fd -> do tr <- wait fd "/tr"
>                    putStrLn (show tr))

> withSC3 (\fd -> do send fd (notify False)
>                    wait fd "/done")