patchgit-gui: add config value gui.diffopts for passing additional diff options

>Signed-off-by: Tilman Vogel <tilman.vogel@web.de>
>---
> Documentation/config.txt |    4 ++++
> git-gui/git-gui.sh       |    1 +
> git-gui/lib/diff.tcl     |    1 +
> git-gui/lib/option.tcl   |    1 +
> 4 files changed, 7 insertions(+), 0 deletions(-)
>
>diff --git a/Documentation/config.txt b/Documentation/config.txt
>index ff7c225..0ed7bcf 100644
>--- a/Documentation/config.txt
>+++ b/Documentation/config.txt
>@@ -1100,6 +1100,10 @@ gui.diffcontext::
> 	Specifies how many context lines should be used in calls to diff
> 	made by the linkgit:git-gui[1]. The default is "5".
> 
>+gui.diffopts::
>+	Specifies additional parameters to pass to diff from 
>+	linkgit:git-gui[1]. The default is "".
>+
> gui.encoding::
> 	Specifies the default encoding to use for displaying of
> 	file contents in linkgit:git-gui[1] and linkgit:gitk[1].
>diff --git a/git-gui/git-gui.sh b/git-gui/git-gui.sh
>index d3acf0d..2a3aed5 100755
>--- a/git-gui/git-gui.sh
>+++ b/git-gui/git-gui.sh
>@@ -823,6 +823,7 @@ set default_config(gui.fastcopyblame) false
> set default_config(gui.copyblamethreshold) 40
> set default_config(gui.blamehistoryctx) 7
> set default_config(gui.diffcontext) 5
>+set default_config(gui.diffopts) {}
> set default_config(gui.commitmsgwidth) 75
> set default_config(gui.newbranchtemplate) {}
> set default_config(gui.spellingdictionary) {}
>diff --git a/git-gui/lib/diff.tcl b/git-gui/lib/diff.tcl
>index dcf0711..de3827a 100644
>--- a/git-gui/lib/diff.tcl
>+++ b/git-gui/lib/diff.tcl
>@@ -295,6 +295,7 @@ proc start_show_diff {cont_info {add_opts {}}} {
> 
> 	lappend cmd -p
> 	lappend cmd --color
>+	set cmd [concat $cmd $repo_config(gui.diffopts)]
> 	if {$repo_config(gui.diffcontext) >= 1} {
> 		lappend cmd "-U$repo_config(gui.diffcontext)"
> 	}
>diff --git a/git-gui/lib/option.tcl b/git-gui/lib/option.tcl
>index 3807c8d..1e5d28c 100644
>--- a/git-gui/lib/option.tcl
>+++ b/git-gui/lib/option.tcl
>@@ -153,6 +153,7 @@ proc do_options {} {
> 		{i-20..200 gui.copyblamethreshold {mc "Minimum Letters To Blame Copy On"}}
> 		{i-0..300 gui.blamehistoryctx {mc "Blame History Context Radius (days)"}}
> 		{i-1..99 gui.diffcontext {mc "Number of Diff Context Lines"}}
>+		{t gui.diffopts {mc "Additional Diff Parameters"}}
> 		{i-0..99 gui.commitmsgwidth {mc "Commit Message Text Width"}}
> 		{t gui.newbranchtemplate {mc "New Branch Name Template"}}
> 		{c gui.encoding {mc "Default File Contents Encoding"}}

> Am 25.01.2011 01:25, schrieb Pat Thoyts:
>> This seems ok but you don't say what it is for. Why do you want to be
>> able to pass additional options to git diff?
> 
> Sorry, forgot to copy the motivation from
> <https://github.com/git/git/pull/8>:
> 
> I want to be able to make diff ignore whitespace changes "-b". But maybe
> someone else wants "-w" or what not, so I think a generic option field
> is most versatile.