Reduce CPU when idle
Introduced an idle flag that will bypass processing and invoke a sleep state in the main loop, if we know for sure that nothing needs to be done. Reduces CPU usage from ~3% to ~1.3% on hidevideo.
[omxplayer] Allow small audio packets to be concatenated to make better use of audio fifo

Some audio codecs produce small packets which causes a high overhead when submitting to GPU, and doesn't make full use of GPU side buffering.
TrueHD in particular can produce packets with 40 samples (so 1200 packets per second) which causes very high overhead.

What this aims to do is to concatenate audio packets until they approach the ideal audio packet size,
and then deal with the awkardness of concatenated planar formats.
reader: Ensure the nonblocking flag is set before avformat_open_input

Fixes issue with streams hanging when network connection is lost
audio: When in dual audio mode, make analogue the slave
Allow selection of video rendering layer
Added --layer n to command line. This changes the video rendering layer to the selected value. The background layer, if turned on, is set to the selected value -1. The subtitle layer is set to the selected value +1.
Merge pull request #168 from microwavesafe/dev_layer

Allow selection of video rendering layer
Merge pull request #164 from microwavesafe/dev

Reduce CPU when idle