(1) We supply the former version of allheaders.h.
         (2) all .c files simply include allheaders.h.

   First, make xtractprotos:
       make xtractprotos

   Then to generate the prototypes and make allheaders.h, do one of
   these two things:
       make allheaders  [puts everything into allheaders.h]
       make allprotos   [generates a file leptprotos.h containing the
                         function prototypes, and includes it in allheaders.h]

   Things to note about xtractprotos, assuming that 