This adds a new tor-hspow crate with the first layers of support in
place for onion service client puzzles as described in Proposal 327.
The API here is experimental, and it's currently only implementing
the self-contained parts of the client puzzle. So, it can verify and
solve puzzles, but it has no event loop integration or nonce replay
tracking or prioritization code yet. These things seem like they would
eventually live in the same crate.
Signed-off-by: Micah Elizabeth Scott <beth@torproject.org>
Micah Elizabeth Scott