Fix servomatic build. Hopefully resolve confusion wrt linesize and

Fix servomatic build.  Hopefully resolve confusion wrt linesize and
stride for FilterBufferImage; the linesize can apparently sometimes
be (slightly) larger than the width for byte-per-pixel images (e.g.
YUV420P).  Remove grotty peek-style socket communication and use a
hopefully more robust send of the length of data as a binary word
before the data itself.  Should fix #62.