Function optimise 

pub fn optimise(model: &mut Model, init: &[f32], options: &Options) -> Optimised

Fit G1/G2 so the simulated pedal matches model, starting from the responses in init (2048 floats of upload data, normally a Measure::Clean conversion). Runs the model over the test signal once, then options.steps simulations; about a minute per 300 steps in an optimised build.