-split off MQ API into separate C file to reduce visibility of symbols; reindentation, stylistic fixes

git-svn-id: https://gnunet.org/svn/gnunet@34544 140774ce-b5e7-0310-ab8b-a85725594a96
-doxygen, one more statistic

git-svn-id: https://gnunet.org/svn/gnunet@34545 140774ce-b5e7-0310-ab8b-a85725594a96
properly clean up pending advertisement message requests with CORE on peer disconnect

git-svn-id: https://gnunet.org/svn/gnunet@34546 140774ce-b5e7-0310-ab8b-a85725594a96