made the weights independent of the situation (training or cross-validation)
removed opt.w = 2 as the weights have been made independent of the situation(training or cross-validation)
getting up to date
will replace classif_recog as performance metric in the unbalanced set case, to be coherent with classif_err
removed the opt.w = 2 case and normalized weights to handle both cross_validation and "real training"
suppressed the value 2 for w and replaced classif_recog by classif_mean_recog