-debug logic for NAT external IP resolution

git-svn-id: https://gnunet.org/svn/gnunet@31705 140774ce-b5e7-0310-ab8b-a85725594a96
-remove OLD, not new

git-svn-id: https://gnunet.org/svn/gnunet@31706 140774ce-b5e7-0310-ab8b-a85725594a96
-doxygen

git-svn-id: https://gnunet.org/svn/gnunet@31707 140774ce-b5e7-0310-ab8b-a85725594a96