Bump copyright year.

gitstats

@@ -1,5 +1,5 @@
 #!/usr/bin/env python
-# Copyright (c) 2007-2012 Heikki Hokkanen <hoxu@users.sf.net> & others (see doc/author.txt)
+# Copyright (c) 2007-2013 Heikki Hokkanen <hoxu@users.sf.net> & others (see doc/author.txt)
 # GPLv2 / GPLv3
 import datetime
 import getopt