Add method to seralize public input

[recmo]

On 2020-04-29 @pvienhage wrote in 7850bac “Smart contrat Recurance proof system impl (#677)”:

Add method to seralize public input

    let trace_length = constraints.trace_nrows();
    let trace_cols = constraints.trace_ncolumns();
    let eval_domain_size = trace_length * constraints.blowup;

    let mut channel = VerifierChannel::new(proof.to_vec());
    // TODO - Add method to seralize public input
    channel.initialize(constraints.channel_seed());

    // Get the low degree root commitment, and constraint root commitment
    // TODO: Make it work as channel.read()
    let low_degree_extension_root: Hash = channel.replay();

From crypto/stark/src/solidity_seralizer.rs:71