scripts/get_maintainer.pl: use mailmap in name deduplication and other updates

Use Florian Mickler's mailmap routine to reduce name duplication.

o Add subroutine deduplicate_email to centralize code
o Add hashes for deduplicate_(name|address)_hash
o Remove now unused @interactive_to
o Whitespace neatening
o Add command line --help text
o Add --mailmap command line option control
o Interactive changes:
   - Add toggles for maintainer, git and list selections
   - Default selection is all
   - Add mailmap control

Update to 0.26-beta5
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>