Migration of builtin-blame to parse-option

This series is twofold. The first 4 patches refactor the revision parsing machine so that it's easier to deal with from a parse-opt based parser:

[PATCH 1/6] revisions: refactor init_revisions and setup_revisions. 21 files changed, 70 insertions(+), 54 deletions(-)

  This is the patch I sent before, revisited.

[PATCH 2/6] revisions: split the pure option parsing out from parse_revisions. 2 files changed, 273 insertions(+), 308 deletions(-)

  This patch splits out the revisions _option_ parsing (as opposed to
  revisions arguments or pseudo arguments like --all, --not, ...) from
  the revision parser. The patch is huge, but quite straightforward.

[PATCH 3/6] revisions: parse_revisions refactor. 1 files changed, 38 insertions(+), 25 deletions(-)

  This patch reworks parse_revisions so that it works internally as if
  it was a parse-opt parser. It's equivalent to the previous code, but
  changes are tricky, and a separate commit is really worth it.

[PATCH 4/6] revisions: split handle_revision_args from parse_revisions. 2 files changed, 52 insertions(+), 46 deletions(-)

  This patch splits out the last bit of parse-revisions (from the
  previous commit) so that what parses revisions arguments (refs and
  pseudo arguments like --all/--not/...) can be called independently.

  The commit is straightforward but moves code around, hence the
  separate commit from patch 3 so that one isn't lost in the code moves
  while reviewing the tricky bits from patch 3.

The second part is the git-blame migration for real:

[PATCH 5/6] git-blame: migrate to incremental parse-option [1/2] 1 files changed, 118 insertions(+), 102 deletions(-)

  This bit is really alike the proof of concept I saw. Most of the code
  is stolen from Linus initial patch. It merely removes the git-blame
  own options and deal with them with a parse-opt parser, in an
  incremental way.

  All in all, it's a pretty straighforward patch.

[PATCH 6/6] git-blame: migrate to incremental parse-option [2/2] 1 files changed, 40 insertions(+), 92 deletions(-)

  This is by far the trickiest patch of the series, though it passes the
  testsuite fine. This patch uses the function from patch 4 to process
  the revision arguments. We know the dashdash position from the
  incremental parse-opt, but we have to deal with the "old way" of
  passing arguments to git-blame.

  The new code is really less involved than before, because we deal with
  a filtered argv array where we only have the revisions arguments (no
  options anymore) and the <path>.