Final method2 implementation

Hcal 25ns reconstruction method2 implementation with fast fitter
(quoted from an email exchange & posted here)
The HybridMinimizer is a copy of the Minuit2Minimizer with some modification. The reason is that Minuit2Minimzer does not allow me to switch the fitting from migrad to scan within itself. I have to make two separate instances for each of the configuration (migrad or scan). But this won't give me the advantage I have in the TFitterMinuit implementation, because the scan part improves the overall fit (technically, I think the scan finds a new "state" and passes the state to migrad for further fitting within the TFitterMinuit). Any rule strongly against having the HybridMinimzer there (even temporarily as further improvement expected, e.g., NNLS)?
        P.S., the fitting (always been used and has been validated) procedure is actually at least: migrad -> scan -> migrad  for every rechit (passing some threshold).