textconv for show and grep

This min series aims at completing the textconv support of user facing commands. It is RFC for lack of documentation and tests, to check whether we really want to go in that direction (I do).

1/4 covers the missing textconv support in the "blob case" of "git show", which should be (and then is) analogous to "cat-file" and "diff".

2/4 remedies an oddity of "git cat-file --textconv", which errored out when there is no textconv filter rather than giving an unfiltered blob (like every other textconv aware command).

3/4 implements "--textconv" for "git grep" sans the blob case; the code is all Jeff's.

4/4 adds blob support to 3/4 (the "rev:path" case).

3 and 4 can be squashed, of course.

Now I'm quite a happy differ/shower/grepper with my latin1 and OO files ;)

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

Michael J Gruber (3):
show: obey --textconv for blobs
cat-file: do not die on --textconv without textconv filters
grep: obey --textconv for the case rev:path

 builtin/cat-file.c           |   9 ++--
 builtin/grep.c               |  13 +++---
 builtin/log.c                |  24 +++++++++--
 grep.c                       | 100 +++++++++++++++++++++++++++++++++++++------
 grep.h                       |   1 +
 object.c                     |  26 ++++++++---
 object.h                     |   2 +
 t/t8007-cat-file-textconv.sh |  20 +++------
 8 files changed, 148 insertions(+), 47 deletions(-)

1.8.1.2.752.g32d147e