first steps towards removing session_impl dependency from tracker connections, to improve their testability

git-svn-id: http://libtorrent.googlecode.com/svn/trunk@10421 f43f7eb3-cfe1-5f9d-1b5f-e45aa6702bda
fix bug in setup_transfer (for unit tests). fix verbose logging build. make sure test_pex is reliable

git-svn-id: http://libtorrent.googlecode.com/svn/trunk@10422 f43f7eb3-cfe1-5f9d-1b5f-e45aa6702bda
fix tracker_manager argument forwarding

git-svn-id: http://libtorrent.googlecode.com/svn/trunk@10423 f43f7eb3-cfe1-5f9d-1b5f-e45aa6702bda