scripts/get_maintainer.pl: use case insensitive name de-duplication

scripts/get_maintainer.pl: use case insensitive name de-duplication

Case insensitive name and email address matching can help reduce
duplication when authors don't always use the exact same signature.

o Add a --interactive per-file exact_match hash so git history
  can be checked on per-file only when there is no direct maintainer
o Make @interactive_to list global so save_commits_by_<foo> can check
  email names & addresses against this list for duplication
o Don't allow --interactive and --sections
o rename subroutine get_maintainer to get_maintainers
o Added help text option to --interactive menu prompt

Update version to 0.26-beta4

Signed-off-by: Joe Perches <joe@perches.com>
Cc: Florian Mickler <florian@mickler.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>