-extend transport plugin API with capability to just disconnect a single session (not yet used)

git-svn-id: https://gnunet.org/svn/gnunet@31300 140774ce-b5e7-0310-ab8b-a85725594a96
remove debugging breaks


git-svn-id: https://gnunet.org/svn/gnunet@31301 140774ce-b5e7-0310-ab8b-a85725594a96
- don't confirm channels scheduled for destruction, client handles are NULL'd

git-svn-id: https://gnunet.org/svn/gnunet@31302 140774ce-b5e7-0310-ab8b-a85725594a96
- don't send ack on channels to be destroyed


git-svn-id: https://gnunet.org/svn/gnunet@31303 140774ce-b5e7-0310-ab8b-a85725594a96