Make API more safe

[olehmisar]

Users may accidentally forget to call jwt.verify(). Is there any reason not to combine .init and .verify into a single function?

Before:

let jwt = JWT::init(
    data,
    b64_offset: u32,
    pubkey_modulus_limbs,
    redc_params_limbs,
    signature_limbs,
);
jwt.verify();

After:

let jwt = JWT::verify(
    data,
    b64_offset: u32,
    pubkey_modulus_limbs,
    redc_params_limbs,
    signature_limbs,
);

Also, for partial hashing:

let jwt = JWT::verify_with_partial_hash(
    partial_data,
    partial_hash,
    full_data_length,
    b64_offset,
    pubkey_modulus_limbs,
    redc_params_limbs,
    signature_limbs,
);