Add update_copyright.py script

git-svn-id: https://svn.osgeo.org/gdal/trunk@27043 f0d54148-0727-0410-94bb-9a71ac55c965
Update copyright

git-svn-id: https://svn.osgeo.org/gdal/trunk@27044 f0d54148-0727-0410-94bb-9a71ac55c965