* snarf.h: New file.

* snarf.h: New file.
* guile-snarf.sh: New file.
* Makefile.in (inner_h_files): Added snarf.h
(ancillary, install, uninstall, distclean): Added actions for
guile-snarf.
(.c.x): Use guile-snarf.
(guile-snarf): New rule, to produce guile-snarf from guile-snarf.sh.
(gen_c_files): Note that these depend on guile-snarf.
* _scm.h: Removed the snarfing macros (SCM_PROC, etc). They are
now in "snarf.h".  Added #include "snarf.h" to get them.
* configure.in: Added guile-snarf to AC_OUTPUT
* libguile.h: Added #include "snarf.h".
(Patches applied and tweaked by Jim Blandy.)