* New: non-8-bits planar 4:2:0 formats (9/10/12/14/16-bits) supports
use event rather than mutex
+some cosmetic changes

since new event has been posted already in order to call QQuickItem::update().
With change of buffered frame mode, I don't need mutex anymore in renderer.
* New: more verbose playback information (output format conversion)
add performance item in preferences