clean up peer-id in bt_peer_connection (for privacy mode) and reduce dependency on session

git-svn-id: http://libtorrent.googlecode.com/svn/trunk@9903 f43f7eb3-cfe1-5f9d-1b5f-e45aa6702bda
improve error recovery in lazy bdecoder

git-svn-id: http://libtorrent.googlecode.com/svn/trunk@9905 f43f7eb3-cfe1-5f9d-1b5f-e45aa6702bda