Deinitialise the clock and free more resources
Restore termio in more exception cases
Check for passthrough being supported before enabling
Improvements to buffering.

After first buffer wait for queues to fill before resuming
Support ffmpeg 1.2 and float planar format

Note: requires recent firmware for float audio support (384946 or later)
Need bigger chunksize for some codecs
Don't query PCM info when in passthough mode, it returns an error