correct implementation of ReverseCharSequence.subSequence
(cherry picked from commit 43a124a)
external annotator is allowed to decide if it should handle file with error + review CR-IC
                                   (cherry picked from commit 88a2716)
ExternalAnnotator documentation is improved +review CR-IC-2315
(cherry picked from commit e3335f6)
ExternalAnnotator: compatibility with older clients is restored; typo fixed in collectInformation name + review CR-IC-2315
(cherry picked from commit 4e10a46)