gitk: Fix display of copyright symbol

The script file uses utf-8 encoding but when sourced it will be read
using the default system encoding which is never utf8 on windows.
This causes the copyright symbol to display incorrectly in the about
dialog.  Using the unicode escape sequence avoids incorrect decoding
but does require a double escape in the .po files.

Also adjusted the year range.

Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/gitk b/gitk
index 9da0526..db8977d 100755
--- a/gitk
+++ b/gitk
@@ -2787,7 +2787,7 @@
     message $w.m -text [mc "
 Gitk - a commit viewer for git
 
-Copyright © 2005-2009 Paul Mackerras
+Copyright \u00a9 2005-2010 Paul Mackerras
 
 Use and redistribute under the terms of the GNU General Public License"] \
 	    -justify center -aspect 400 -border 2 -bg white -relief groove