[Discuss-gnuradio] gr-audio OSX fixes test branch

[Michael Dickens]

I just pushed the latest WIP for fixing gr-audio on OSX; I hope some 
adventurous OSX users can test this branch out & provide feedback!  If you want 
to help, but don't know how, ask me and I'll provide instructions. - MLD

< https://github.com/michaelld/gnuradio/tree/fix_gr_audio_osx >

Fixes that I've tested and seem to work for me:

+ device selection via command line/instantiation arguments (e.g., "dial_tone 
-O foo" or "audio_fft -I bar");
+ device selection by full or partial name, case sensitive (for now; e.g., 
"audio_fft -O FUN" to get the "FUNcube Dongle" device);
+ correct sample rate detection and use for non-Apple provided audio devices 
(e.g., FUNcube Dongle).

Fix that I have not yet tested but should work:

+ flow-graph start/stop.

Fixes that I'm still working on:

+ if the default audio device is used (meaning, no audio device name is 
specified at instantiation), then track when the user changes the default audio 
device and switch to using it;
+ if a removable device is selected (default or directly), then track if the 
device is removed and switch to another device.