TODO List:
- Add support for frame metadata (timecode, frame type, ...), as reported by
  struct v4l2_buffer.
- Add support for MPEG format
- Add a control to adjust the frame rate when ioctl(VIDIOC_S_PARM) is supported
- Add methods to set multiple extended controls at once
- Add probe for more drivers (need some help from people having hardware for 
  that).
- libvideo is NOT reentrant and does NOT implement a proper locking scheme yet.
  Therefore, it is the caller's responsibility to ensure accesses to libvideo
  are synchronised.

