more work towards sending ethernet frames with compressed video
stream.
put frame synchronisation marker at end of frame instead of
beginning, so that it is safe to write it out without fearing that
pixel data will follow the next cycle.  also gives ethernet time
to push the remaining data out.
simplify and correct video stream buffering in framebuffer.
plumb in video buffer so that ethernet should start sending real
compressed video frames.  there look to be bugs in the video
frame data.
add video streaming modules to ISE project.