support read-only DHT nodes

git-svn-id: svn://svn.code.sf.net/p/libtorrent/code/branches/RC_1_0@10379 a83610d8-ad2a-0410-a6ab-fc0612d85776
improve utp_dynamic_sock_buf option to not shrink the kernel socket buffer size to unreasonable sizes

git-svn-id: svn://svn.code.sf.net/p/libtorrent/code/branches/RC_1_0@10380 a83610d8-ad2a-0410-a6ab-fc0612d85776
improve test_metadata_extension

git-svn-id: svn://svn.code.sf.net/p/libtorrent/code/branches/RC_1_0@10381 a83610d8-ad2a-0410-a6ab-fc0612d85776
add assert and make test_fast_extension more reliable

git-svn-id: svn://svn.code.sf.net/p/libtorrent/code/branches/RC_1_0@10386 a83610d8-ad2a-0410-a6ab-fc0612d85776
super seeding fix

git-svn-id: svn://svn.code.sf.net/p/libtorrent/code/branches/RC_1_0@10387 a83610d8-ad2a-0410-a6ab-fc0612d85776
make super seeding test stricter

git-svn-id: svn://svn.code.sf.net/p/libtorrent/code/branches/RC_1_0@10388 a83610d8-ad2a-0410-a6ab-fc0612d85776