* gnulib-tool (func_usage): Document options --hardlink,
--local-hardlink, --more-hardlinks.
(func_symlink): Renamed from func_ln.
(func_symlink_if_changed): Renamed from func_ln_if_changed.
(func_hardlink): New function.
(copymode, lcopymode): New variables.
(symbolic, lsymbolic): Remove variables.
(Options): Implement options --hardlink, --local-hardlink,
--more-hardlinks.
(func_should_link): Renamed from func_should_symlink. Set copyaction.
(func_add_file, func_update_file): Update invocation of
func_should_link. Invoke func_hardlink when appropriate.
(func_import): Update comments.
(func_create_testdir): Update invocation of func_should_link. Invoke
func_hardlink when appropriate.
Finally, invoke 'git update-index --refresh' to mitigate the effects of
the hard links on git.