git-gui: Display all authors of git-gui.

Now that git-gui has been released to the public as part of Git 1.5.0
I am starting to see some work from other people beyond myself and
Paul.  Consequently the copyright for git-gui is not strictly the
two of us anymore, and these others deserve to have some credit
given to them.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
diff --git a/git-gui.sh b/git-gui.sh
index 63848dc..cd3afed 100755
--- a/git-gui.sh
+++ b/git-gui.sh
@@ -4,7 +4,7 @@
 
 set appvers {@@GITGUI_VERSION@@}
 set copyright {
-Copyright © 2006, 2007 Shawn Pearce, Paul Mackerras.
+Copyright © 2006, 2007 Shawn Pearce, et. al.
 
 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
@@ -19,6 +19,9 @@
 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA}
+set gitgui_credits {
+Paul Mackerras
+}
 
 ######################################################################
 ##
@@ -4477,6 +4480,61 @@
 	commit_tree
 }
 
+proc do_credits {} {
+	global gitgui_credits
+
+	set w .credits_dialog
+
+	toplevel $w
+	wm geometry $w "+[winfo rootx .]+[winfo rooty .]"
+
+	label $w.header -text {git-gui Contributors} -font font_uibold
+	pack $w.header -side top -fill x
+
+	frame $w.buttons
+	button $w.buttons.close -text {Close} \
+		-font font_ui \
+		-command [list destroy $w]
+	pack $w.buttons.close -side right
+	pack $w.buttons -side bottom -fill x -pady 10 -padx 10
+
+	frame $w.credits
+	text $w.credits.t \
+		-background [$w.header cget -background] \
+		-yscrollcommand [list $w.credits.sby set] \
+		-width 20 \
+		-height 10 \
+		-wrap none \
+		-borderwidth 1 \
+		-relief solid \
+		-padx 5 -pady 5 \
+		-font font_ui
+	scrollbar $w.credits.sby -command [list $w.credits.t yview]
+	pack $w.credits.sby -side right -fill y
+	pack $w.credits.t -fill both -expand 1
+	pack $w.credits -side top -fill both -expand 1 -padx 5 -pady 5
+
+	label $w.desc \
+		-text "All portions are copyrighted by their respective authors
+and are distributed under the GNU General Public License." \
+		-padx 5 -pady 5 \
+		-justify left \
+		-anchor w \
+		-borderwidth 1 \
+		-relief solid \
+		-font font_ui
+	pack $w.desc -side top -fill x -padx 5 -pady 5
+
+	$w.credits.t insert end "[string trim $gitgui_credits]\n"
+	$w.credits.t conf -state disabled
+	$w.credits.t see 1.0
+
+	bind $w <Visibility> "grab $w; focus $w"
+	bind $w <Key-Escape> [list destroy $w]
+	wm title $w [$w.header cget -text]
+	tkwait window $w
+}
+
 proc do_about {} {
 	global appvers copyright
 	global tcl_patchLevel tk_patchLevel
@@ -4493,6 +4551,10 @@
 	button $w.buttons.close -text {Close} \
 		-font font_ui \
 		-command [list destroy $w]
+	button $w.buttons.credits -text {Contributors} \
+		-font font_ui \
+		-command do_credits
+	pack $w.buttons.credits -side left
 	pack $w.buttons.close -side right
 	pack $w.buttons -side bottom -fill x -pady 10 -padx 10