Corrected YCbCr -> RGB conversion
Corrected YCbCr -> RGB conversion

The code I snarfed from Cortado was borked in some way and was
not quite the right color. Redid using floating point from
formula in Wikipedia. ;)

Not sure if it's best to use floating point here, but default
JS engines would be doing math as FP anyway. Should fix the int
version and benchmark some time.

paladox/ogv.js,paladox/ogv.js,chrislearn/ogv.js,chrislearn/ogv.js,xzf158/ogv.js,paladox/ogv.js,paladox/ogv.js,xzf158/ogv.js,xzf158/ogv.js,xzf158/ogv.js,chrislearn/ogv.js,chrislearn/ogv.js,chrislearn/ogv.js,xzf158/ogv.js,paladox/ogv.js