Plonk: change handling of PI & Sid polynomials, by adding non-commited polynomials - Fixes #25

Modifies query’s type by adding a new field non_commited, which contains a StringMap {"P" -> (Poly.polynomial P, fun (x -> P(x))} ; the first element will be use only by prover, and the second only by verifier. Polynomials of non_commited are directly computed by verifier and don’t go through Polynomial Commitement. These special polynomials are Sids and PI.

Add public inputs in test_main_protocol.test_big_circuit.

Made on top of !49 (merged)