With this approach, we don't need `Target::PublicInput`; any routable `Target` can be marked as a public input via `register_public_input`. The circuit itself hashes these targets, and routes the hash output to the first four wires of a `PublicInputGate`, which is placed at an arbitrary location in the circuit.
All gates have direct access to the purported hash of public inputs. We could think of them as accessing `PI_hash_i(x)` (as in Plonk), but these are now (four) constant functions, so they effectively have direct access to the hash itself.
`PublicInputGate` checks that its first four wires match this purported public input hash. The other gates ignore the hash.
Resolves#64.
* Make ZK optional
* Remove rate from FriConfig
Seems redundant, and we've had some tests break due to the two fields not matching.
* zero_knowledge: false in bench
Using `serde_cbor` for now. It's probably far from optimal, as we have many `Vec`s which I assume it will prefix with their lengths, but it's a nice and easy method for now.
Does this make sense? I think other libraries tend to include the leaf's index (either as an integer, or a series of bits indicating left/right turns) as part of a "proof". In FRI, the leaf indices are chosen by the verifier, so I thought that approach might be sort of redundant. Let me know what you think though.
