improve utp_dynamic_sock_buf option to not shrink the kernel socket buffer size to unreasonable sizes

git-svn-id: http://libtorrent.googlecode.com/svn@10380 f43f7eb3-cfe1-5f9d-1b5f-e45aa6702bda
improve test_metadata_extension

git-svn-id: http://libtorrent.googlecode.com/svn@10381 f43f7eb3-cfe1-5f9d-1b5f-e45aa6702bda
merge changes from RC_1_0

git-svn-id: http://libtorrent.googlecode.com/svn@10382 f43f7eb3-cfe1-5f9d-1b5f-e45aa6702bda
make test_metadata_extension test uTP vs. TCP as well, and polish output

git-svn-id: http://libtorrent.googlecode.com/svn@10383 f43f7eb3-cfe1-5f9d-1b5f-e45aa6702bda