This, along with custom DTMF twist values of 20 in dsp.conf, seem to
be required to get coins to be detected through the mouthpiece of my
payphone

Updated ACTS patch for Asterisk 13.11.2

since the tones are played rapidly and are going over the internet,
they might not get heard properly/separately by asterisk. keep
track of the timing (using Time::HiRes) of tones received and if we
hear 3 in less than 0.5 seconds, consider that good enough to count
as a quarter and ignore the 4th and 5th ones we might still hear.