git-gui: Allow users to edit user.name, user.email from options.

Users may need to be able to alter their user.name or user.email
configuration settings.  If they are mostly a git-gui user they
should be able to view/set these important values from within
the git-gui environment, rather than needing to edit a raw text
file on their local filesystem.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

git-gui.sh

@@ -4270,6 +4270,9 @@ proc do_options {} {
 
 	set optid 0
 	foreach option {
+		{t user.name {User Name}}
+		{t user.email {Email Address}}
+
 		{b merge.summary {Summarize Merge Commits}}
 		{i-1..5 merge.verbosity {Merge Verbosity}}
 
@@ -4676,6 +4679,9 @@ proc apply_config {} {
 
 set default_config(merge.summary) false
 set default_config(merge.verbosity) 2
+set default_config(user.name) {}
+set default_config(user.email) {}
+
 set default_config(gui.trustmtime) false
 set default_config(gui.diffcontext) 5
 set default_config(gui.newbranchtemplate) {}