Merge branch 'tr/filter-branch'

Merge branch 'tr/filter-branch'

* tr/filter-branch:
  revision --simplify-merges: make it a no-op without pathspec
  revision --simplify-merges: do not leave commits unprocessed
  revision --simplify-merges: use decoration instead of commit->util field
  Documentation: rev-list-options: move --simplify-merges documentation
  filter-branch: use --simplify-merges
  filter-branch: fix ref rewriting with --subdirectory-filter
  filter-branch: Extend test to show rewriting bug
  Topo-sort before --simplify-merges
  revision traversal: show full history with merge simplification
  revision.c: whitespace fix