-doxygen, style fixes

git-svn-id: https://gnunet.org/svn/gnunet@31347 140774ce-b5e7-0310-ab8b-a85725594a96
-update doxy file

git-svn-id: https://gnunet.org/svn/gnunet@31348 140774ce-b5e7-0310-ab8b-a85725594a96
remove addresses we cannot connect to


git-svn-id: https://gnunet.org/svn/gnunet@31349 140774ce-b5e7-0310-ab8b-a85725594a96
-code cleanup, fixing #3207: timeout can be NULL in reschedule_session_timeout if we are 'in destroy', in which case we should simply do nothing

git-svn-id: https://gnunet.org/svn/gnunet@31350 140774ce-b5e7-0310-ab8b-a85725594a96