Write documentation
  Include an example explaining how to use cppi as part of a cvs commit hook.

Add overwrite option -- maybe use GNU-style backup code.

Allow regex filtering (use Henry Spencer's new perl-like regexps)
   rather than hard-coding test for .c and .h suffixes

Add an option to enable the following (there's already support for it):
  Uli's suggestion for setting initial indentation level to e.g. -1
  for header files bracketed with #ifdef FOO_H/#define FOO_H...#endif.

Make sure we get a reasonable failure when cppi.l is modified
and flex is not available.

Likewise with cpp.gp and gperf (do this via the `missing' script).


Add gettext support.
