Merge branch 'ab/plug-leak-in-revisions'

Merge branch 'ab/plug-leak-in-revisions'

Plug the memory leaks from the trickiest API of all, the revision
walker.

* ab/plug-leak-in-revisions: (27 commits)
  revisions API: add a TODO for diff_free(&revs->diffopt)
  revisions API: have release_revisions() release "topo_walk_info"
  revisions API: have release_revisions() release "date_mode"
  revisions API: call diff_free(&revs->pruning) in revisions_release()
  revisions API: release "reflog_info" in release revisions()
  revisions API: clear "boundary_commits" in release_revisions()
  revisions API: have release_revisions() release "prune_data"
  revisions API: have release_revisions() release "grep_filter"
  revisions API: have release_revisions() release "filter"
  revisions API: have release_revisions() release "cmdline"
  revisions API: have release_revisions() release "mailmap"
  revisions API: have release_revisions() release "commits"
  revisions API users: use release_revisions() for "prune_data" users
  revisions API users: use release_revisions() with UNLEAK()
  revisions API users: use release_revisions() in builtin/log.c
  revisions API users: use release_revisions() in http-push.c
  revisions API users: add "goto cleanup" for release_revisions()
  stash: always have the owner of "stash_info" free it
  revisions API users: use release_revisions() needing REV_INFO_INIT
  revision.[ch]: document and move code declared around "init"
  ...