Update legal information.
All source files of xgsch2pcb have outdated legal headers.
Current version has old FSF address:
# 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
New one:
# 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.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
Same situation with COPYING. Can it be replaced by
http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt ?
Closes-bug: lp-
1054248