LoopbackAudio: Read back from write-tail
LoopbackAudio: Read back from write-tail

Watching an HTML5 video on youtube in Safari obviously broke
my assumption of a fixed offset between read- and write sample-times.

Let's try reading relative to the write-tail instead.

q-p/SoundPusher,q-p/SoundPusher,q-p/SoundPusher