Quad - bugfixes

 * format is now entered as a parameter string (-g <mode>)
 * expect currently buffers as big as needed (exactly one frame)
   TODO: revide if isn't possible to read whole buffer at once
   (ideally the memmapped one, and extract frames by hand)
 * now it is needed to set /sys/class/sdivideo/sdivideorxX/bufsize
 * bump to new driver (2.7.2)