TODO for v4l2loopback in no specific order

- fix all bugs :-)

- improve buffering (salsaman)

- allow USERPTR buffers

- allow to use the device without streaming i/o

- pass 'v4l2-compliance' tests
  currently failing are:
	VIDIOC_G/S_PRIORITY
	VIDIOC_LOG_STATUS
	VIDIOC_ENUMAUDIO
	VIDIOC_G/S_AUDIO
	VIDIOC_ENUMAUDOUT
	VIDIOC_G/S/ENUMOUTPUT
	VIDIOC_G/S_CTRL
	VIDIOC_G/S/TRY_EXT_CTRLS
	VIDIOC_ENUM/G/S/QUERY_STD
	VIDIOC_ENUM/G/S/QUERY_DV_PRESETS
	VIDIOC_ENUM_FMT/FRAMESIZES/FRAMEINTERVALS
	VIDIOC_G_FBUF
	VIDIOC_G_FMT
	VIDIOC_G_SLICED_VBI_CAP

- it would be nice to have a way to communicate format requests from the
  consumer to the producer (though i see no way how to do that)

- provide more producers for more colorspaces in the examples