fix typo in audio entry point
example audio (a sine at around 440hz)
first working coreaudio hal implementation

we query for the prefered stereo channels, then
configure the streams containing those channels, and register the
channels to write to for our IO Proc.

the IO proc then finds its audiobuffers, query the client
for samples, then puts them into the hw buffer.

Somehow I get the sense that Apple would prefer me to use the AUHAL
audio unit.

To do: better error handing (those printfs are ugly)