Add new options to configure audio and video file reading queues, and audio and video GPU fifo sizes

--audio_fifo  n           Size of audio output fifo in seconds
--video_fifo  n           Size of video output fifo in MB
--audio_queue n           Size of audio input queue in MB
--video_queue n           Size of video input queue in MB
More care with going into and out of buffering.

Try to wait for GPU fifos to be full before resuming from buffering.
Use pre-roll mecahnism from clock.