fix setyp.py

git-svn-id: svn://svn.code.sf.net/p/libtorrent/code/branches/RC_1_0@10485 a83610d8-ad2a-0410-a6ab-fc0612d85776
support overlong utf-8 sequences. fix single-file torrent case where name contains a full path, make the mapping to filenames more intuitive and extend the unit tests

git-svn-id: svn://svn.code.sf.net/p/libtorrent/code/branches/RC_1_0@10489 a83610d8-ad2a-0410-a6ab-fc0612d85776