Adding --version command line option

It would be nice if gcl supported a --version option to print out the gcl
version. This should probably just print out what
(lisp-implementation-version) prints, for consistency.

Handy for scripts that want or need to know the version.

More convenient than having to figure out how to use -eval and friends to
print it out, and so many gnu programs already support --version.
-- 
Ray