When querying a listview subitem for the user param, the main item's
user param is returned. Also, when a subitem is custom-drawn, the main
item's user param is passed along.

With help from Ken Thomases.

make_makefiles: In .gitignore, explicitly list files that we know are generated instead of using wildcards.

Also, added some output formats that Core Audio ought to be able to handle.

wodSendNotifyInputCompletionsMessage sends the kWaveInNotifyCompletionsMessage
to the message thread, which calls widHelper_NotifyCompletions.

It scans for completed input wavehdrs, removes them from the queue,
and notifies the application that they're done.

It now returns in an output parameter the frame count that the AU will use.
Also, initialize the Audio Unit.

It will serve as the input callback called when our Audio Unit has sound
data available.

With grateful acknowledgement to Marcus Meissner.