0.8.13.70: MORE DOCUMENTATION

0.8.13.70: MORE DOCUMENTATION
            * Include documentation, however sparse, for SB-PROFILE,
               SB-GRAY, and SB-SIMPLE-STREAMS.
            * Beginnings of restructuring the manual: lift
               SB-BSD-SOCKETS into a full chapter called "Networking",
               etc.
            * An unfortunate consequence of the above is that we
               cannot autogenerate the contrib-doc list anymore, and
               the contrib documentation structure is less otrhogonal
               and has tighter coupling to the general manual structure.
               Since new contribs appear relatively seldom this is
               hopefully not a big issue.