matrixfit, fit.effectivemass: Make the computation of errors on the fit parameters through bootstrapping optional, even if bootstrap samples are used to compute the inverse of the covariance matrix for the fit. This saves time if one is checking the distribution of fit results as a function of the fit range, for example
fit.effectivemass: when boot.fit=FALSE, explicitly set massfit.tsboot to NA
computefps: make bootstrapping of the decay constant computation optional