-fix #3158

git-svn-id: https://gnunet.org/svn/gnunet@31132 140774ce-b5e7-0310-ab8b-a85725594a96
-dox

git-svn-id: https://gnunet.org/svn/gnunet@31133 140774ce-b5e7-0310-ab8b-a85725594a96
- fixed compile warning


git-svn-id: https://gnunet.org/svn/gnunet@31134 140774ce-b5e7-0310-ab8b-a85725594a96
basic qr code reading


git-svn-id: https://gnunet.org/svn/gnunet@31135 140774ce-b5e7-0310-ab8b-a85725594a96