[PATCH v1 0/3] Introduce config variable "diff.primer"

The next three patches introduce a way to specify diff options
git always obeys. Then use the new feature to
enhance git-gui with white space ignore settings.  The fastest
way to see this patch in action is: apply all three patches,
fire up git-gui, modify a file, then right-click on the diff
panel and look for the new "White Space" sub-menu.

Future work: Extend the gitattributes mechanism so it supports
all [diff] config variables, including e.g. diff.mnemonicprefix
and diff.primer.

Keith Cascio (3):
 Introduce config variable "diff.primer"
 Test functionality of new config variable "diff.primer"
 git-gui hooks for new config variable "diff.primer"

 Documentation/config.txt       |   14 +++++
 Documentation/diff-options.txt |   13 +++++
 Makefile                       |    2 +
 builtin-log.c                  |    1 +
 diff.c                         |   83 ++++++++++++++++++++++++++----
 diff.h                         |   15 ++++-
 git-gui/git-gui.sh             |   51 ++++++++++++++++++
 git-gui/lib/diff.tcl           |    8 ++-
 git-gui/lib/option.tcl         |   57 +++++++++++++++++++--
 gitk-git/gitk                  |   16 +++---
 t/t4033-diff-primer.sh         |  111 ++++++++++++++++++++++++++++++++++++++++
 11 files changed, 343 insertions(+), 28 deletions(-)
 create mode 100755 t/t4033-diff-primer.sh