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.
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.
Merge branch 'master' of https://github.com/ktws/omxplayer