scripts/get_maintainer.pl: improve --interactive UI

o Added searching by git-blame as well as git-history
o Added different selection toggles
o Added ability to list commits by author or by sign-off-type
o Use custom git and hg formats to make searching for subject/author
  a bit easier.
o Move inlined section matching and searching git/hg history to
  new get_maintainer subroutine
o Added subroutines save_commits_by_author and save_commits_by_signer
o Removed subroutines vcs_get_shortlog and vcs_email_shortlog
o Rename camelcase signaturePattern to signature_pattern

Update to 0.26 beta3
Signed-off-by: NJoe Perches <joe@perches.com>
Cc: Florian Mickler <florian@mickler.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>