Merge branch 'pw/rebase-i-more-options'

"git rebase -i" learns a bit more options. * pw/rebase-i-more-options: t3436: do not run git-merge-recursive in dashed form rebase: add --reset-author-date rebase -i: support --ignore-date rebase -i: support --committer-date-is-author-date am: stop exporting GIT_COMMITTER_DATE rebase -i: add --ignore-whitespace flag