web seed and storage fixes

git-svn-id: http://libtorrent.googlecode.com/svn@10020 f43f7eb3-cfe1-5f9d-1b5f-e45aa6702bda
back-ported web seed fix from trunk

git-svn-id: http://libtorrent.googlecode.com/svn@10021 f43f7eb3-cfe1-5f9d-1b5f-e45aa6702bda
merged changes from trunk

git-svn-id: http://libtorrent.googlecode.com/svn@10022 f43f7eb3-cfe1-5f9d-1b5f-e45aa6702bda
tag 0.16.17 release

git-svn-id: http://libtorrent.googlecode.com/svn@10023 f43f7eb3-cfe1-5f9d-1b5f-e45aa6702bda
remove 'drop skipped requests' feature

git-svn-id: http://libtorrent.googlecode.com/svn@10024 f43f7eb3-cfe1-5f9d-1b5f-e45aa6702bda