textconv with grep and show

This is the "Git Merge edition" of the textconv series. Great conference, the series struggles to match that.

v3 keeps all defaults as they are (no textconv for blobs by default) and incorporates Junio's touched_flags patch. I do not need the callback but left it in.

As for beeing able to choose textconv as a default for blobs, I'm wondering how fine grained that needs to be: one for all, differentiate between "show blob" and "grep", or even driver specific (diff.driver.blobtextconv boolean).

In the latter case, it's not clear to me how "--textconv" with a "false" config should behave.

Jeff King (1):
grep: allow to use textconv filters

Junio C Hamano (1):
diff_opt: track whether flags have been set explicitly

Michael J Gruber (5):
t4030: demonstrate behavior of show with textconv
show: honor --textconv for blobs
cat-file: do not die on --textconv without textconv filters
t7008: demonstrate behavior of grep with textconv
grep: honor --textconv for the case rev:path

 Documentation/git-grep.txt           |   9 +++-
 Documentation/technical/api-diff.txt |  10 +++-
 builtin/cat-file.c                   |  18 +++----
 builtin/grep.c                       |  13 +++--
 builtin/log.c                        |  26 +++++++--
 diff.c                               |   3 ++
 diff.h                               |   8 ++-
 grep.c                               | 100 ++++++++++++++++++++++++++++++-----
 grep.h                               |   1 +
 object.c                             |  26 ++++++---
 object.h                             |   2 +
 t/t4030-diff-textconv.sh             |  24 +++++++++
 t/t7008-grep-binary.sh               |  31 +++++++++++
 t/t8007-cat-file-textconv.sh         |  20 ++-----
 14 files changed, 234 insertions(+), 57 deletions(-)

1.8.3.rc1.406.gf4dce7e