improve printing of bencoded structures

git-svn-id: svn://svn.code.sf.net/p/libtorrent/code@10470 a83610d8-ad2a-0410-a6ab-fc0612d85776
tweak flag_override_resume_data semantics to make more sense (breaks backwards compatibility of edge-cases)

git-svn-id: svn://svn.code.sf.net/p/libtorrent/code@10471 a83610d8-ad2a-0410-a6ab-fc0612d85776